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Review Article |

Implantable Cardioverter-Defibrillator Shocks:  Epidemiology, Outcomes, and Therapeutic Approaches FREE

Ryan T. Borne, MD; Paul D. Varosy, MD; Frederick A. Masoudi, MD, MSPH
[+] Author Affiliations

Author Affiliations: Department of Medicine, Denver Health and Hospital Authority (Dr Borne), Veterans Affairs Eastern Colorado Healthcare System (Dr Varosy), and Colorado Cardiovascular Outcomes Research Consortium (Drs Varosy and Masoudi), Denver, and Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora (Drs Borne, Varosy, and Masoudi).


JAMA Intern Med. 2013;173(10):859-865. doi:10.1001/jamainternmed.2013.428.
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Published online

Importance Implantable cardioverter-defibrillators (ICDs) have revolutionized the approach to the prevention of sudden cardiac death and are commonly used in a wide range of high-risk patients, including the large population of patients with severe left ventricular systolic dysfunction. The benefit of these devices derives from their therapies, including both antitachycardia pacing and high-energy shocks. However, although these therapies may be life saving, devices can also deliver inappropriate shocks.

Objective To review ICD therapies (shocks and antitachycardia pacing), their effects on health outcomes, and current methods to reduce these therapies.

Evidence Review We reviewed clinical evidence on ICD shocks and reference lists of retrieved articles. We also examined literature about the methods of reducing ICD therapy.

Findings Both appropriate and inappropriate ICD shocks are common and are associated with an adverse effect on health outcomes, quality of life, and mortality. Several methods are available to reduce the risk of inappropriate ICD therapies.

Conclusions and Relevance Implantable cardioverter-defibrillators reduce the risk of sudden cardiac death and prolong life in selected populations; however, many patients will receive an ICD shock, either appropriate or inappropriate. It is imperative that patients be counseled regarding this risk and adverse outcomes associated with shocks. Reduction of ICD shock should be individualized to ensure that patients receiving these devices experience the maximal benefits of therapy while minimizing the adverse consequences.

Figures in this Article

A 56-year-old man with an ischemic cardiomyopathy and a left ventricular ejection fraction of 30% presents for routine follow-up. He recently had an implantable cardioverter-defibrillator (ICD) placed for primary prevention of sudden cardiac death (SCD); he has no history of ventricular arrhythmias. During the interview, the patient describes an ICD shock that occurred while he was exercising at the gym. He relates that this has occurred a few other times in the past. He is tired of worrying that his device is about to shock him and wants to resume a “normal life.” An interrogation of his ICD identifies that these shocks have been triggered by sinus tachycardia; there has been no evidence of ventricular tachycardia (VT). As his cardiologist, primary care physician, or other health care professional, what do you do next?

Implantable cardioverter-defibrillators have revolutionized the treatment of individuals at high risk for SCD. Since the first ICD was implanted in 1980, the indications for this intervention have expanded both because of the evolution of device technology and in the clinical science supporting the use of ICDs.1 After the publication of landmark randomized clinical trials and adoption in multiple professional guidelines, ICDs are frequently used for the primary prevention of SCD in patients with left ventricular systolic dysfunction (LVSD).24 From January 1, 2006, through December 31, 2009, 486 025 ICD implants were documented in the ICD Registry of the National Cardiovascular Data Registry, which is estimated to account for 90% of all ICDs implanted in the United States during this period.5 As the number of patients receiving ICDs increases rapidly, the potential consequences associated with inappropriate ICD shocks have received greater attention. This article reviews ICD therapies (shocks and antitachycardia pacing [ATP]), their effects on health outcomes, and current methods at attempting to reduce these therapies.

Sudden cardiac death is often due to ventricular arrhythmias, which are particularly common in patients with LVSD. Implantable cardioverter-defibrillators are used to recognize and promptly treat these malignant ventricular arrhythmias, often implementing high-energy shocks for defibrillation. The event the patient experiences is a sudden intracardiac shock akin to external defibrillation. Patients have described an ICD shock as “an earthquake,” “being hit by a truck,” or “being kicked by a mule.”6 Given the traumatic nature of ICD shocks, it would be ideal if the ICD could always successfully distinguish ventricular arrhythmias from non–life-threatening tachyarrhythmias and administer shocks only for VT or ventricular fibrillation (VF) (ie, appropriate shocks).7 Unfortunately, in practice, the algorithms that discriminate VT or VF from less lethal arrhythmias have not been perfected. Furthermore, many patients with an ICD—as many as 1 in 3 in some studies—receive inappropriate shocks.8 Inappropriate shocks occur when the device delivers a high-voltage discharge for a reason other than a ventricular arrhythmia. Thus, although the primary role of the ICD is to detect ventricular arrhythmias and to deliver therapies to restore normal sinus rhythm (including both ATP and shocks), this benefit comes at some cost to those patients who receive inappropriate shocks for non–life-threatening rhythms and other reasons.

Although the reported frequency of ICD shocks varies, a consistent finding is that substantial proportions of patients receive shocks after ICD implantation. In patients receiving ICDs in the secondary prevention Antiarrhythmics versus Implantable Defibrillators (AVID) trial, the proportion of patients with an arrhythmic event, defined as SCD, sustained ventricular arrhythmia, or ICD therapy, was 35% at 3 months, 53% at 1 year, and 68% at 2 years.9 Approximately 45% of patients had a shock within the first year. In a meta-analysis of 7 major ICD trials, appropriate ICD therapy (including both ATP and shock) occurred in up to 64% and inappropriate therapies occurred in up to 24% during 20 to 45 months of follow-up (Figure 1).13 Among the 194 000 patients included in a large, observational, prospective study, appropriate and inappropriate shock rates at 5 years were 23% and 17%, respectively.14 Compared with earlier studies, roughly half of 422 patients (52%) analyzed in a prospective cohort experienced appropriate ICD therapy at a median follow-up of 3.6 years, suggesting that the incidence of appropriate ICD therapy may have declined in recent years.15 Expanding indications for use of ICD implantation (primary prevention) have resulted in a selection of patients who are less likely to experience malignant ventricular arrhythmias than the secondary prevention population. In addition, compared with these earlier trials, the implementation of specific strategies may reduce the rates of avoidable and inappropriate ICD shocks. Thus, the actual risk of inappropriate shocks in contemporary practice may be lower than those documented in the clinical efficacy trials of ICDs.

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Figure 1. Appropriate and inappropriate implantable cardioverter-defibrillator (ICD) shock rates from the Multicenter Automatic Defibrillator Implantation Trial (MADIT II),10 the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT),4,8 Defibrillators in Non-Ischemic Cardiomyopathy Treatment Evaluation (DEFINITE) trial,3,11 and the Antiarrhythmics versus Implantable Defibrillators (AVID) trial.9,12

Implantable cardioverter-defibrillators are configured with zones demarcated by particular heart rate settings above which the device is programmed to deliver some type of therapy. The so-called VF zone is typically programmed to identify arrhythmias with faster rates, for example, more than 180 to 200/min, or a cycle length of 300 to 330 milliseconds. Thereafter, if the device senses a rate faster than this programmed rate and the other criteria are met, including detection algorithms and duration or number of intervals at that rate, the device is programmed to deliver therapies, including ATP and/or high-energy discharges. Unfortunately, not all patterns of electrograms that meet the diagnostic criteria for detection in the VF zone are VF or even other ventricular arrhythmias; it is these non-VT or non-VF detections that result in inappropriate therapies from the device. Inappropriate shocks are most commonly a result of supraventricular tachycardias (SVTs), including sinus tachycardia, atrial fibrillation (AF), or atrial flutter with rapid ventricular response. Supraventricular tachycardias are capable of meeting heart rate and duration criteria for which the device is programmed to deliver shocks and are accountable for more than 90% of inappropriate detection resulting in therapy (Figure 2).9,16 The Multicenter Automatic Defibrillator Implantation Trial (MADIT II) found that AF and atrial flutter were the most common SVTs to cause inappropriate ICD shocks (Figure 3).10

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Figure 2. Reasons for inappropriate arrhythmia detection among patients with implantation of a combined cardiac resynchronization therapy–implantable cardioverter-defibrillator (ICD) device in the Multicenter InSync ICD Randomized Clinical Evaluation study.8,16

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Figure 3. Reasons for inappropriate implantable cardioverter-defibrillator (ICD) shock among patients with ischemic cardiomyopathy and reduced left ventricular ejection fraction who received a primary prevention ICD in the Multicenter Automatic Defibrillator Implantation Trial.10

Technical failures of the ICD generator or leads can result in unpredictable device behavior, including in appropriate shock. Technical causes of inappropriate ICD shock include faulty components, oversensing of electrical noise, lead fracture, electromagnetic interference, oversensing of diaphragm myopotentials, oversensing of T waves, and double counting of QRS complexes.17 Recently, there have been widely publicized Food and Drug Administration Class 1 Product Advisories (recalls) of ICD leads, specifically the Medtronic Sprint Fidelis and the St Jude Medical Riata leads. These recalls resulted from evidence of high rates of lead failure, in some cases manifest as inappropriate ICD shocks.1820 In a study of long-term performance of ICD leads in the Veterans Affairs system, the failure rates of both the Medtronic Sprint Fidelis and St Jude Medical Riata leads were substantially greater than conventional benchmarks.21 In addition, of the St Jude Medical Riata leads that failed, almost 30% resulted in one or more inappropriate shock. Particularly among patients with leads and/or pulse generators known to have higher than expected rates of failure, hardware failure should be considered in the differential diagnosis of ICD shocks.

Ventricular pacing may increase the risk of VT or VF through various mechanisms, including mechanical ventricular irritability at the site of the lead implantation and increased the risk of inducing scar-based reentrant ventricular arrhythmias among patients with myocardial fibrosis.22,23 In MADIT II, higher rates of right ventricular pacing were associated with higher rates of appropriate therapies for VT or VF and new or worsened heart failure.24 Finally, right ventricular pacing among ICD recipients is associated with increased mortality, possibly due to induction of left ventricular dyssynchrony and worsening heart failure.25

Certain patients are at higher risk for any ICD shock. In a community-based study, appropriate ICD therapy was more likely in patients receiving ICD therapy for secondary prevention, who were older, or who had lower left ventricular ejection fraction.15 Post hoc analyses from the randomized clinical trials have also identified risk factors for inappropriate ICD shocks. In a substudy of MADIT II, patients with AF, tobacco use, and diastolic hypertension had a higher risk of inappropriate shocks; in the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT), inappropriate shocks were more frequent in patients with nonischemic heart failure compared with those with ischemic heart disease.8,26 Inappropriate ICD shocks are presumably more common in patients with AF because of rapid ventricular response rates that meet the heart rate threshold to trigger shocks. The mechanisms of the association between the other factors and ICD shocks are unclear.

There is little controversy that ICD therapy can prolong life in appropriately selected patients with LVSD because of the ability to abort arrhythmic SCD with defibrillation. However, several studies have found that the life-prolonging benefit of an ICD shock comes with a cost and is associated with adverse outcomes.

Studies in several settings suggest that health-related quality of life is influenced adversely in patients who experience ICD shocks, regardless of whether they are appropriate or inappropriate. In the SCD-HeFT trial—a primary prevention randomized controlled trial—patients who received shocks within 1 month of a scheduled assessment (n = 49) had substantially lower health-related quality of life than those who had not received shocks in the previous month.27 In the secondary prevention setting in the AVID trial, patients who had experienced at least one shock had significantly poorer mental well-being and physical functioning.28

Implantable cardioverter-defibrillator shocks are also associated with psychological disorders. Anxiety is particularly common, with 24% to 87% of patients with an ICD experiencing worsened symptoms and diagnosis of anxiety disorders.29 Patients who experienced more shocks were significantly more anxious and depressed than the group not experiencing shocks.30,31 Among 95 ICD recipients, those who experienced more than 5 shocks developed significantly higher anxiety than other ICD recipients.32 Godemann et al33 evaluated 90 patients with ICDs using a standardized interview that focused on the diagnosis of anxiety disorders. Panic disorder and/or agoraphobia were identified in 16.7% of the patients, which was markedly higher than the general population. Patients who had an ICD shock had a 21% prevalence of these diagnoses vs a 6.9% prevalence in those patients without an ICD shock. Patients with an ICD are under substantial risk of psychological distress; the number of ICD shocks contributes to these disorders.3032 We do not know of any study that addresses psychological distress confined to patients with inappropriate shock only.

There is increasing evidence that ICD shocks are associated with increased risk of heart failure hospitalization, a particularly concerning finding given the high baseline rates of hospitalization in patients with LVSD. In a subgroup analysis of MADIT II, the risk of a heart failure event at 1 year was 26% and 31% after first treatment for VT and VF, respectively, compared with 19% for those without ICD therapy.34

Finally, clinical trials have identified an association between ICD shock and mortality. MADIT II found that appropriate ICD therapy identifies more than a 3-fold increase in mortality risk.34 In the SCD-HeFT trial, both appropriate and inappropriate ICD shocks were significant predictors of death, increasing risk of death by 5- and 2-fold, respectively.8 Of 2135 ICD patients analyzed by Sweeney et al,35 shock for ventricular arrhythmias was associated with a 20% increase in mortality, whereas no change was noted in mortality among those with ATP-treated arrhythmias. The most common cause of death among patients with ICD shock was progressive heart failure.

Although there is little dispute regarding the association of ICD shock and adverse outcome, the meaning of this relationship is unclear. A potential explanation for these apparent associations is that ICD shocks might cause adverse outcomes by inducing myocardial injury; however, it is perhaps more likely the case that patients who are sicker and who have poorer functional status more often experience ventricular arrhythmias. This finding is illustrated in the prospective cohort who demonstrated that patients with inappropriate ICD shock due to technical failure (noise and oversensing) were not at increased risk of mortality, supporting the claim that ICD shocks are a marker rather than a mediator of adverse outcomes.14

ICD Programming

Antitachycardia pacing for VT is a safe and effective alternative to shocks for terminating many ventricular arrhythmias. With ATP, the ICD delivers a burst of ventricular-paced beats at a rate faster than the underlying arrhythmia. This approach will often terminate reentrant arrhythmias, even monomorphic VTs as fast as 240/min, obviating the need for shocks in many cases. To date, large-scale trials have found that ATP may effectively terminate more than 90% of spontaneous VT.36 The advantages of ATP over shock include less patient discomfort, less battery drain, and possibly lower risks of adverse health outcomes.37 Therefore, ATP is preferred as the initial therapy for many monomorphic VTs unless otherwise contraindicated.

Two large-scale trials have addressed specific programming strategies to reduce the need for ICD shock. First, ATP for VT faster than 200/min, which had been traditionally treated by shock because of safety concerns, reduced the need for shock and improved quality of life with little risk of VT acceleration and syncope and no difference in mortality.38 Second, the aggressive use of ATP, SVT discriminators, and high-output first shock compared with a historical control cohort of patients who had ICD parameters programmed at the discretion of their physician lowered the risk for any shock during the first year (8.5% vs 16.9%).39

Recently, the MADIT–Reduce Inappropriate Therapy trial evaluated whether more stringent ventricular arrhythmia detection algorithms and, once arrhythmias are detected, more aggressive use of ATP would reduce inappropriate therapies.40 Patients with primary prevention ICDs were randomly assigned to 1 of 3 programming configurations to evaluate rates of inappropriate ICD therapy. At a mean follow-up of 1.4 years, the high-rate therapy (initiation of therapy at >199/min) and delayed ICD therapy (with a 60-second delay at 170 to 199/min, a 12-second delay at 200-249/min, and 2.5-second delay at >249/min) groups compared with conventional device programming significantly reduced the first and total occurrence of both appropriate and inappropriate therapy. More important, the conventional treatment group had a significantly higher cumulative mortality during follow-up compared with both of the new programming strategies.

Other programming features may also reduce the likelihood of ICD shocks. On the basis of the observation that VT tends to be abrupt in onset and somewhat regular (high stability), sinus tachycardia tends to accelerate gradually, and AF is irregularly irregular (low stability), Brugada et al41 found that programming sudden onset and stability criteria helped discriminate supraventricular arrhythmias and reduced the risk of inappropriate shock. In addition, just as the surface QRS complex during VT generally differs from that during sinus rhythm, discrimination algorithms can be used to identify the differences in the contour of the sensed intracardiac electrograms compared with a template of the electrograms during known sinus rhythm.42 Although all devices are preprogrammed, it is important for the implanting clinician to review the device settings because these settings may be inappropriate for the individual patient.

Dual-Chamber ICDs

A dual-chamber ICD might theoretically help distinguish SVT from VT by using atrial and ventricular sensing information to discriminate between the 2 arrhythmias. Detecting atrioventricular dissociation can help distinguish VT from SVT not only by using surface electrocardiography but also via the sensed device electrograms. Conceptually, the idea is that a ventricular rate of 200/min with an atrial rate of 75/min would be consistent with VT; in contrast, a ventricular rate of 110/min with an atrial rate of 350/min suggests SVT (likely AF). However, data supporting dual-chamber devices as a means of improving arrhythmia discrimination are limited; no study reports that dual-chamber device programming is effective at reducing the risk of inappropriate ICD shocks.4346 In addition, the potential benefits of dual-chamber devices must be weighed against the costs and risks of this therapy. Dual-chamber devices are more expensive and are associated with higher periprocedural complication rates than single-chamber ICDs.47,48

Pharmacologic Therapy

Select antiarrhythmic medications can be used to reduce the frequency of ICD shocks. The mechanisms of benefit include suppressing atrial and ventricular arrhythmias and slowing episodes of VT, which may allow patients to better tolerate VT hemodynamically, thereby allowing for broader use of ATP.

Evidence-based heart failure therapy with β-blockers, angiotensin-converting enzyme inhibitors, and aldosterone receptor antagonists reduce the risk of heart failure hospitalization and mortality (including SCD) among patients with LVSD.4953 These therapies are underused in eligible patients undergoing ICD implantation, which, in turn, may add to the burden of ICD shocks.54,55 Optimal medical therapy may result in improvement of left ventricular systolic function such that ICD therapy may no longer be warranted. In addition, medical therapy offers improvements in symptoms of heart failure, mortality, and the risk of ventricular arrhythmias, resulting in ICD therapies. Further, β-blockers may reduce ventricular rates in patients with supraventricular arrhythmias, such as AF, which could prevent inappropriate ICD shocks.

Optimal heart failure therapy alone may be inadequate to prevent shocks. In a randomized trial comparing a β-blocker alone, amiodarone and a β-blocker, or sotalol, 40% of patients treated with β-blockers alone had shocks at 1 year, whereas those treated with amiodarone and β-blockers had only a 10% risk.56 Thus, all patients with LVSD should receive optimal heart failure therapy, and in selected patients, additional rhythm control therapy may be warranted.

Antiarrhythmic medications also have limitations. Most are potentially proarrhythmic; sotalol has a considerable (1%-4%) risk of triggering torsades de pointes, especially among patients taking higher doses (>320 mg/d), with elevated serum creatinine levels, with a history of VT or heart failure, and of female sex.57 Amiodarone causes many important and sometimes severe extracardiac toxic effects.58,59 The addition of antiarrhythmic medications needs to be individualized, considering the number of shocks, the effect of these shocks on the patient, and risk of adverse effects of the medications.

Catheter Ablation

Catheter-based ablation techniques are also used to treat ventricular arrhythmias. The typical indication for ablation is VT refractory to medical therapy in patients who also receive multiple ICD shocks. The prophylactic use of catheter ablation on the rate of ICD therapy in secondary prevention patients was examined with 128 patients who were randomized to either catheter ablation using a substrate-based approach or no ablation.60 In the ablation group, there was a 65% lower risk of receiving ICD therapy (ATP or shock) and a 73% lower risk of receiving ICD shocks. However, ablation had no significant effect on mortality, and no data were collected on quality of life. Furthermore, ablation was conducted at highly experienced centers, is exceptionally operator dependent, and is not widely available. In addition, although there were no reported adverse effects of ablation, the procedure inherently carries with it multiple potential complications. Given the lack of evidence and clinical trials supporting the widespread use of ablation techniques, it should not be considered clinically indicated as prophylaxis to reduce ICD therapy.

Optimizing Evidence-Based ICD Implantation

Because patients who do not undergo ICD implantation will not receive inappropriate (or appropriate) ATP or shocks, any strategy to minimize inappropriate device therapies should begin with ensuring that the decision to implant an ICD is based on established indications outlined in the relevant clinical guidelines.61,62 Rigorous adherence to current evidence in selecting patients for ICD implantation will ensure that treatment is provided to those for whom the benefits are expected to outweigh the risks of therapy, including the risks of inappropriate ICD shocks. A recent study63 suggests that patient selection for primary prevention ICD therapy could be improved.

The patient in the clinical vignette received multiple inappropriate ICD shocks for sinus tachycardia while exercising. At the time of ICD implantation, the manufacturer's default programming settings had been used, including a lower-limit VF zone starting at 180/min. To minimize his risk of inappropriate ICD shock, his device was reprogrammed to a higher-threshold heart rate for the VF zone, and his β-blocker dose was increased. He has since been free of inappropriate ICD shocks while maintaining his active exercise regimen.

Implantable cardioverter-defibrillators reduce the risk of SCD from ventricular arrhythmias, thus prolonging life in selected high-risk patients. However, it is important that patients understand that many with ICDs receive a shock; indeed, the benefit of the device results from its treatment of malignant ventricular arrhythmias. Unfortunately, shocks may also be delivered inappropriately (ie, for nonlethal rhythms). Furthermore, shocks, both appropriate and inappropriate, may have consequences for health status and other important health outcomes.

After careful selection, once a patient undergoes implantation, the first step in reducing adverse outcomes should be to minimize any ICD shock to the extent possible, acknowledging that the primary purpose of the device is to treat malignant ventricular arrhythmias, often with shocks. All patients should have programming with individual settings based on history and demographics; aggressive use of ATP; and appropriate use and dosing of evidence-based therapies for LVSD, including β-blockers, angiotensin-converting enzyme inhibitors, and aldosterone antagonists when appropriate. Other approaches, including use of dual-chamber ICDs and catheter ablation, are still controversial. The therapeutic approach should be individualized to ensure that patients receiving ICDs experience the maximal benefits of therapy while minimizing the possible adverse consequences.

Correspondence: Ryan T. Borne, MD, Denver Health Medical Center, 660 Bannock St, MC 4000, Denver, CO 80204 (ryan.borne@dhha.org).

Accepted for Publication: December 12, 2012.

Published Online: April 1, 2013. doi:10.1001/jamainternmed.2013.428

Author Contributions:Study concept and design: All authors. Acquisition of data: Borne and Masoudi. Analysis and interpretation of data: All authors. Drafting of the manuscript: Borne and Masoudi. Critical revision of the manuscript for important intellectual content: All authors. Administrative, technical, and material support: Borne. Study supervision: Borne and Varosy.

Conflict of Interest Disclosures: None reported.

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Dougherty CM. Psychological reactions and family adjustment in shock versus no shock groups after implantation of internal cardioverter defibrillator.  Heart Lung. 1995;24(4):281-291
PubMed   |  Link to Article
Luderitz B, Jung W, Deister A, Manz M. Quality of Life in Multiprogrammable Implantable Cardioverter-Defibrillator Recipients: Interventional Electrophysiology: A Textbook. In: Saskena S, Luderitz B, eds. Armonk, NY: Futura Publishing Co Inc; 1996:305-313
Godemann F, Butter C, Lampe F,  et al.  Panic disorders and agoraphobia: side effects of treatment with an implantable cardioverter/defibrillator.  Clin Cardiol. 2004;27(6):321-326
PubMed   |  Link to Article
Moss AJ, Greenberg H, Case RB,  et al; Multicenter Automatic Defibrillator Implantation Trial-II (MADIT-II) Research Group.  Long-term clinical course of patients after termination of ventricular tachyarrhythmia by an implanted defibrillator.  Circulation. 2004;110(25):3760-3765
PubMed   |  Link to Article
Sweeney MO, Sherfesee L, DeGroot PJ, Wathen MS, Wilkoff BL. Differences in effects of electrical therapy type for ventricular arrhythmias on mortality in implantable cardioverter-defibrillator patients.  Heart Rhythm. 2010;7(3):353-360
PubMed   |  Link to Article
Nasir NJ Jr, Pacifico A, Doyle TK, Earle NR, Hardage ML, Henry PD.Cadence Investigators.  Spontaneous ventricular tachycardia treated by antitachycardia pacing.  Am J Cardiol. 1997;79(6):820-822
PubMed   |  Link to Article
Estes NA III, Haugh CJ, Wang PJ, Manolis AS. Antitachycardia pacing and low-energy cardioversion for ventricular tachycardia termination: a clinical perspective.  Am Heart J. 1994;127(4 Pt 2):1038-1046
PubMed   |  Link to Article
Wathen MS, DeGroot PJ, Sweeney MO,  et al; PainFREE Rx II Investigators.  Prospective randomized multicenter trial of empirical antitachycardia pacing versus shocks for spontaneous rapid ventricular tachycardia in patients with implantable cardioverter-defibrillators: Pacing Fast Ventricular Tachycardia Reduces Shock Therapies (PainFREE Rx II) trial results.  Circulation. 2004;110(17):2591-2596
PubMed   |  Link to Article
Wilkoff BL, Williamson BD, Stern RS,  et al;  PREPARE Study Investigators.  Strategic programming of detection and therapy parameters in implantable cardioverter-defibrillators reduces shocks in primary prevention patients: results from the PREPARE (Primary Prevention Parameters Evaluation) study.  J Am Coll Cardiol. 2008;52(7):541-550
PubMed   |  Link to Article
Moss AJ, Schuger C, Beck CA,  et al; MADIT-RIT Trial Investigators.  Reduction in inappropriate therapy and mortality through ICD programming.  N Engl J Med. 2012;367(24):2275-2283
PubMed   |  Link to Article
Brugada J, Mont L, Figueiredo M, Valentino M, Matas M, Navarro-López F. Enhanced detection criteria in implantable defibrillators.  J Cardiovasc Electrophysiol. 1998;9(3):261-268
PubMed   |  Link to Article
Klein GJ, Gillberg JM, Tang A,  et al; Worldwide Wave Investigators.  Improving SVT discrimination in single-chamber ICDs: a new electrogram morphology-based algorithm.  J Cardiovasc Electrophysiol. 2006;17(12):1310-1319
PubMed   |  Link to Article
Kühlkamp V, Dörnberger V, Mewis C, Suchalla R, Bosch RF, Seipel L. Clinical experience with the new detection algorithms for atrial fibrillation of a defibrillator with dual chamber sensing and pacing.  J Cardiovasc Electrophysiol. 1999;10(7):905-915
PubMed   |  Link to Article
Deisenhofer I, Kolb C, Ndrepepa G,  et al.  Do current dual chamber cardioverter defibrillators have advantages over conventional single chamber cardioverter defibrillators in reducing inappropriate therapies? a randomized, prospective study.  J Cardiovasc Electrophysiol. 2001;12(2):134-142
PubMed   |  Link to Article
Theuns DA, Klootwijk AP, Goedhart DM, Jordaens LJ. Prevention of inappropriate therapy in implantable cardioverter-defibrillators: results of a prospective, randomized study of tachyarrhythmia detection algorithms.  J Am Coll Cardiol. 2004;44(12):2362-2367
PubMed   |  Link to Article
Friedman PA, McClelland RL, Bamlet WR,  et al.  Dual-chamber versus single-chamber detection enhancements for implantable defibrillator rhythm diagnosis: the Detect Supraventricular Tachycardia Study.  Circulation. 2006;113(25):2871-2879
PubMed   |  Link to Article
Dewland TA, Pellegrini CN, Wang Y, Marcus GM, Keung E, Varosy PD. Dual-chamber implantable cardioverter-defibrillator selection is associated with increased complication rates and mortality among patients enrolled in the NCDR Implantable Cardioverter-Defibrillator Registry.  J Am Coll Cardiol. 2011;58(10):1007-1013
PubMed   |  Link to Article
Cheng A, Wang Y, Curtis JP, Varosy PD. Acute lead dislodgements and in-hospital mortality in patients enrolled in the National Cardiovascular Data Registry Implantable Cardioverter Defibrillator Registry.  J Am Coll Cardiol. 2010;56(20):1651-1656
PubMed   |  Link to Article
Hjalmarson A, Goldstein S, Fagerberg B,  et al; MERIT-HF Study Group.  Effects of controlled-release metoprolol on total mortality, hospitalizations, and well-being in patients with heart failure: the Metoprolol CR/XL Randomized Intervention Trial in Congestive Heart Failure (MERIT-HF).  JAMA. 2000;283(10):1295-1302
PubMed   |  Link to Article
Packer M, Bristow MR, Cohn JN,  et al; U.S. Carvedilol Heart Failure Study Group.  The effect of carvedilol on morbidity and mortality in patients with chronic heart failure.  N Engl J Med. 1996;334(21):1349-1355
PubMed   |  Link to Article
Packer M, Coats AJ, Fowler MB,  et al; Carvedilol Prospective Randomized Cumulative Survival Study Group.  Effect of carvedilol on survival in severe chronic heart failure.  N Engl J Med. 2001;344(22):1651-1658
PubMed   |  Link to Article
Flather MD, Yusuf S, Køber L,  et al; ACE-Inhibitor Myocardial Infarction Collaborative Group.  Long-term ACE-inhibitor therapy in patients with heart failure or left-ventricular dysfunction: a systematic overview of data from individual patients.  Lancet. 2000;355(9215):1575-1581
PubMed   |  Link to Article
Bapoje SR, Bahia A, Hokanson JE,  et al.  The effects of mineralcorticoid receptor antagonists on the risk of sudden cardiac death in patients with left ventricular systolic dysfunction: a meta-analysis of randomized controlled trials.  Cir Heart Failhttp://circheartfailure.ahajournals.org/content/early/2013/02/12/CIRCHEARTFAILURE.112.000003.abstract.html. Accessed February 12, 2013
Hauptman PJ, Swindle JP, Masoudi FA, Burroughs TE. Underutilization of β-blockers in patients undergoing implantable cardioverter-defibrillator and cardiac resynchronization procedures.  Circ Cardiovasc Qual Outcomes. 2010;3(2):204-211
PubMed   |  Link to Article
Masoudi FA, Gross CP, Wang Y,  et al.  Adoption of spironolactone therapy for older patients with heart failure and left ventricular systolic dysfunction in the United States, 1998-2001.  Circulation. 2005;112(1):39-47
PubMed   |  Link to Article
Connolly SJ, Dorian P, Roberts RS,  et al; Optimal Pharmacological Therapy in Cardioverter Defibrillator Patients (OPTIC) Investigators.  Comparison of β-blockers, amiodarone plus β-blockers, or sotalol for prevention of shocks from implantable cardioverter defibrillators: the OPTIC Study: a randomized trial.  JAMA. 2006;295(2):165-171
PubMed   |  Link to Article
Lehmann MH, Hardy S, Archibald D, Quart B, MacNeil DJ. Sex difference in risk of torsade de pointes with d,l-sotalol.  Circulation. 1996;94(10):2535-2541
PubMed   |  Link to Article
Vorperian VR, Havighurst TC, Miller S, January CT. Adverse effects of low dose amiodarone: a meta-analysis.  J Am Coll Cardiol. 1997;30(3):791-798
PubMed   |  Link to Article
Goldschlager N, Epstein AE, Naccarelli G, Olshansky B, Singh B.Practice Guidelines Subcommitee, North American Society of Pacing, Electrophysiology.  Practical guidelines for clinicians who treat patients with amiodarone. Practice Guidelines Subcommittee, North American Society of Pacing and Electrophysiology.  Arch Intern Med. 2000;160(12):1741-1748
PubMed   |  Link to Article
Reddy VY, Reynolds MR, Neuzil P,  et al.  Prophylactic catheter ablation for the prevention of defibrillator therapy.  N Engl J Med. 2007;357(26):2657-2665
PubMed   |  Link to Article
Epstein AE, DiMarco JP, Ellenbogen KA,  et al; American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices); American Association for Thoracic Surgery; Society of Thoracic Surgeons.  ACC/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines.  J Am Coll Cardiol. 2008;51(21):e1-e62http://content.onlinejacc.org/article.aspx?articleid=1138927. Accessed December 10, 2012
PubMed   |  Link to Article
Tracy CM, Epstein AE, Darbar D,  et al.  2012 ACCF/AHA/HRS focused update incorporated into the ACCF/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. 2012;60(4):1297-1313. http://content.onlinejacc.org/article.aspx?articleid=1357576. Accessed December 10, 2012
Al-Khatib SM, Hellkamp A, Curtis J,  et al.  Non–evidence-based ICD implantations in the United States.  JAMA. 2011;305(1):43-49
PubMed   |  Link to Article

Figures

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Figure 1. Appropriate and inappropriate implantable cardioverter-defibrillator (ICD) shock rates from the Multicenter Automatic Defibrillator Implantation Trial (MADIT II),10 the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT),4,8 Defibrillators in Non-Ischemic Cardiomyopathy Treatment Evaluation (DEFINITE) trial,3,11 and the Antiarrhythmics versus Implantable Defibrillators (AVID) trial.9,12

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Graphic Jump Location

Figure 2. Reasons for inappropriate arrhythmia detection among patients with implantation of a combined cardiac resynchronization therapy–implantable cardioverter-defibrillator (ICD) device in the Multicenter InSync ICD Randomized Clinical Evaluation study.8,16

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Figure 3. Reasons for inappropriate implantable cardioverter-defibrillator (ICD) shock among patients with ischemic cardiomyopathy and reduced left ventricular ejection fraction who received a primary prevention ICD in the Multicenter Automatic Defibrillator Implantation Trial.10

Tables

References

Mirowski M, Reid PR, Mower MM,  et al.  Termination of malignant ventricular arrhythmias with an implanted automatic defibrillator in human beings.  N Engl J Med. 1980;303(6):322-324
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Moss AJ, Zareba W, Hall WJ,  et al; Multicenter Automatic Defibrillator Implantation Trial II Investigators.  Prophylactic implantation of a defibrillator in patients with myocardial infarction and reduced ejection fraction.  N Engl J Med. 2002;346(12):877-883
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Kadish A, Dyer A, Daubert JP,  et al; Defibrillators in Non-Ischemic Cardiomyopathy Treatment Evaluation (DEFINITE) Investigators.  Prophylactic defibrillator implantation in patients with nonischemic dilated cardiomyopathy.  N Engl J Med. 2004;350(21):2151-2158
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Bardy GH, Lee KL, Mark DB,  et al; Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) Investigators.  Amiodarone or an implantable cardioverter-defibrillator for congestive heart failure.  N Engl J Med. 2005;352(3):225-237
PubMed   |  Link to Article
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Ahmad M, Bloomstein L, Roelke M, Bernstein AD, Parsonnet V. Patients' attitudes toward implanted defibrillator shocks.  Pacing Clin Electrophysiol. 2000;23(6):934-938
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Klein RC, Raitt MH, Wilkoff BL,  et al; AVID Investigators.  Analysis of implantable cardioverter defibrillator therapy in the Antiarrhythmics Versus Implantable Defibrillators (AVID) Trial.  J Cardiovasc Electrophysiol. 2003;14(9):940-948
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Daubert JP, Zareba W, Cannom DS,  et al; MADIT II Investigators.  Inappropriate implantable cardioverter-defibrillator shocks in MADIT II: frequency, mechanisms, predictors, and survival impact.  J Am Coll Cardiol. 2008;51(14):1357-1365
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Ellenbogen KA, Levine JH, Berger RD,  et al; Defibrillators in Non-Ischemic Cardiomyopathy Treatment Evaluation (DEFINITE) Investigators.  Are implantable cardioverter defibrillator shocks a surrogate for sudden cardiac death in patients with nonischemic cardiomyopathy?  Circulation. 2006;113(6):776-782
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The Antiarrhythmics versus Implantable Defibrillators (AVID) Investigators.  A comparison of antiarrhythmic-drug therapy with implantable defibrillators in patients resuscitated from near-fatal ventricular arrhythmias.  N Engl J Med. 1997;337(22):1576-1583
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Germano JJ, Reynolds M, Essebag V, Josephson ME. Frequency and causes of implantable cardioverter-defibrillator therapies: is device therapy proarrhythmic?  Am J Cardiol. 2006;97(8):1255-1261
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Saxon LA, Hayes DL, Gilliam FR,  et al.  Long-term outcome after ICD and CRT implantation and influence of remote device follow-up: the ALTITUDE survival study.  Circulation. 2010;122(23):2359-2367
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Koller MT, Schaer B, Wolbers M, Sticherling C, Bucher HC, Osswald S. Death without prior appropriate implantable cardioverter-defibrillator therapy: a competing risk study.  Circulation. 2008;117(15):1918-1926
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Wilkoff BL, Hess M, Young J, Abraham WT. Differences in tachyarrhythmia detection and implantable cardioverter defibrillator therapy by primary or secondary prevention indication in cardiac resynchronization therapy patients.  J Cardiovasc Electrophysiol. 2004;15(9):1002-1009
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Hauser RG, Hayes DL. Increasing hazard of Sprint Fidelis implantable cardioverter-defibrillator lead failure.  Heart Rhythm. 2009;6(5):605-610
PubMed   |  Link to Article
Valk S, Luijten R, Jordaens L. Insulation damage in a shock wire: an unexpected fluoroscopic image.  Pacing Clin Electrophysiol. 2010;33(6):770-772
PubMed   |  Link to Article
Richards MW, Warren CE, Anderson MH. Late failure of a single-coil transvenous implantable cardioverter-defibrillator lead associated with conductor separation.  Europace. 2010;12(8):1191-1192
PubMed   |  Link to Article
Sung RK, Massie BM, Varosy PD,  et al.  Long-term electrical survival analysis of Riata and Riata ST silicone leads: National Veterans Affairs experience.  Heart Rhythm. 2012;9(12):1954-1961
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Himmrich E, Przibille O, Zellerhoff C,  et al.  Proarrhythmic effect of pacemaker stimulation in patients with implanted cardioverter-defibrillators.  Circulation. 2003;108(2):192-197
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Josephson ME. Recurrent Ventricular Tachycardia. Clinical Cardiac Electrophysiology: Techniques and Interpretations. Philadelphia, PA: Lippincott, Williams & Wilkins; 2002
Steinberg JS, Fischer A, Wang P,  et al; MADIT II Investigators.  The clinical implications of cumulative right ventricular pacing in the multicenter automatic defibrillator trial II.  J Cardiovasc Electrophysiol. 2005;16(4):359-365
PubMed   |  Link to Article
Wilkoff BL, Cook JR, Epstein AE,  et al; Dual Chamber and VVI Implantable Defibrillator Trial Investigators.  Dual-chamber pacing or ventricular backup pacing in patients with an implantable defibrillator: the Dual Chamber and VVI Implantable Defibrillator (DAVID) Trial.  JAMA. 2002;288(24):3115-3123
PubMed   |  Link to Article
Vollmann D, Lüthje L, Vonhof S, Unterberg C. Inappropriate therapy and fatal proarrhythmia by an implantable cardioverter-defibrillator.  Heart Rhythm. 2005;2(3):307-309
PubMed   |  Link to Article
Mark DB, Anstrom KJ, Sun JL,  et al; Sudden Cardiac Death in Heart Failure Trial Investigators.  Quality of life with defibrillator therapy or amiodarone in heart failure.  N Engl J Med. 2008;359(10):999-1008
PubMed   |  Link to Article
Schron EB, Exner DV, Yao Q,  et al.  Quality of life in the Antiarrhythmics versus Implantable Defibrillators Trial: impact of therapy and influence of adverse symptoms and defibrillator shocks.  Circulation. 2002;105(5):589-594
PubMed   |  Link to Article
Sears SF Jr, Todaro JF, Lewis TS, Sotile W, Conti JB. Examining the psychosocial impact of implantable cardioverter defibrillators: a literature review.  Clin Cardiol. 1999;22(7):481-489
PubMed   |  Link to Article
Hegel MT, Griegel LE, Black C, Goulden L, Ozahowski T. Anxiety and depression in patients receiving implanted cardioverter-defibrillators: a longitudinal investigation.  Int J Psychiatry Med. 1997;27(1):57-69
PubMed   |  Link to Article
Dougherty CM. Psychological reactions and family adjustment in shock versus no shock groups after implantation of internal cardioverter defibrillator.  Heart Lung. 1995;24(4):281-291
PubMed   |  Link to Article
Luderitz B, Jung W, Deister A, Manz M. Quality of Life in Multiprogrammable Implantable Cardioverter-Defibrillator Recipients: Interventional Electrophysiology: A Textbook. In: Saskena S, Luderitz B, eds. Armonk, NY: Futura Publishing Co Inc; 1996:305-313
Godemann F, Butter C, Lampe F,  et al.  Panic disorders and agoraphobia: side effects of treatment with an implantable cardioverter/defibrillator.  Clin Cardiol. 2004;27(6):321-326
PubMed   |  Link to Article
Moss AJ, Greenberg H, Case RB,  et al; Multicenter Automatic Defibrillator Implantation Trial-II (MADIT-II) Research Group.  Long-term clinical course of patients after termination of ventricular tachyarrhythmia by an implanted defibrillator.  Circulation. 2004;110(25):3760-3765
PubMed   |  Link to Article
Sweeney MO, Sherfesee L, DeGroot PJ, Wathen MS, Wilkoff BL. Differences in effects of electrical therapy type for ventricular arrhythmias on mortality in implantable cardioverter-defibrillator patients.  Heart Rhythm. 2010;7(3):353-360
PubMed   |  Link to Article
Nasir NJ Jr, Pacifico A, Doyle TK, Earle NR, Hardage ML, Henry PD.Cadence Investigators.  Spontaneous ventricular tachycardia treated by antitachycardia pacing.  Am J Cardiol. 1997;79(6):820-822
PubMed   |  Link to Article
Estes NA III, Haugh CJ, Wang PJ, Manolis AS. Antitachycardia pacing and low-energy cardioversion for ventricular tachycardia termination: a clinical perspective.  Am Heart J. 1994;127(4 Pt 2):1038-1046
PubMed   |  Link to Article
Wathen MS, DeGroot PJ, Sweeney MO,  et al; PainFREE Rx II Investigators.  Prospective randomized multicenter trial of empirical antitachycardia pacing versus shocks for spontaneous rapid ventricular tachycardia in patients with implantable cardioverter-defibrillators: Pacing Fast Ventricular Tachycardia Reduces Shock Therapies (PainFREE Rx II) trial results.  Circulation. 2004;110(17):2591-2596
PubMed   |  Link to Article
Wilkoff BL, Williamson BD, Stern RS,  et al;  PREPARE Study Investigators.  Strategic programming of detection and therapy parameters in implantable cardioverter-defibrillators reduces shocks in primary prevention patients: results from the PREPARE (Primary Prevention Parameters Evaluation) study.  J Am Coll Cardiol. 2008;52(7):541-550
PubMed   |  Link to Article
Moss AJ, Schuger C, Beck CA,  et al; MADIT-RIT Trial Investigators.  Reduction in inappropriate therapy and mortality through ICD programming.  N Engl J Med. 2012;367(24):2275-2283
PubMed   |  Link to Article
Brugada J, Mont L, Figueiredo M, Valentino M, Matas M, Navarro-López F. Enhanced detection criteria in implantable defibrillators.  J Cardiovasc Electrophysiol. 1998;9(3):261-268
PubMed   |  Link to Article
Klein GJ, Gillberg JM, Tang A,  et al; Worldwide Wave Investigators.  Improving SVT discrimination in single-chamber ICDs: a new electrogram morphology-based algorithm.  J Cardiovasc Electrophysiol. 2006;17(12):1310-1319
PubMed   |  Link to Article
Kühlkamp V, Dörnberger V, Mewis C, Suchalla R, Bosch RF, Seipel L. Clinical experience with the new detection algorithms for atrial fibrillation of a defibrillator with dual chamber sensing and pacing.  J Cardiovasc Electrophysiol. 1999;10(7):905-915
PubMed   |  Link to Article
Deisenhofer I, Kolb C, Ndrepepa G,  et al.  Do current dual chamber cardioverter defibrillators have advantages over conventional single chamber cardioverter defibrillators in reducing inappropriate therapies? a randomized, prospective study.  J Cardiovasc Electrophysiol. 2001;12(2):134-142
PubMed   |  Link to Article
Theuns DA, Klootwijk AP, Goedhart DM, Jordaens LJ. Prevention of inappropriate therapy in implantable cardioverter-defibrillators: results of a prospective, randomized study of tachyarrhythmia detection algorithms.  J Am Coll Cardiol. 2004;44(12):2362-2367
PubMed   |  Link to Article
Friedman PA, McClelland RL, Bamlet WR,  et al.  Dual-chamber versus single-chamber detection enhancements for implantable defibrillator rhythm diagnosis: the Detect Supraventricular Tachycardia Study.  Circulation. 2006;113(25):2871-2879
PubMed   |  Link to Article
Dewland TA, Pellegrini CN, Wang Y, Marcus GM, Keung E, Varosy PD. Dual-chamber implantable cardioverter-defibrillator selection is associated with increased complication rates and mortality among patients enrolled in the NCDR Implantable Cardioverter-Defibrillator Registry.  J Am Coll Cardiol. 2011;58(10):1007-1013
PubMed   |  Link to Article
Cheng A, Wang Y, Curtis JP, Varosy PD. Acute lead dislodgements and in-hospital mortality in patients enrolled in the National Cardiovascular Data Registry Implantable Cardioverter Defibrillator Registry.  J Am Coll Cardiol. 2010;56(20):1651-1656
PubMed   |  Link to Article
Hjalmarson A, Goldstein S, Fagerberg B,  et al; MERIT-HF Study Group.  Effects of controlled-release metoprolol on total mortality, hospitalizations, and well-being in patients with heart failure: the Metoprolol CR/XL Randomized Intervention Trial in Congestive Heart Failure (MERIT-HF).  JAMA. 2000;283(10):1295-1302
PubMed   |  Link to Article
Packer M, Bristow MR, Cohn JN,  et al; U.S. Carvedilol Heart Failure Study Group.  The effect of carvedilol on morbidity and mortality in patients with chronic heart failure.  N Engl J Med. 1996;334(21):1349-1355
PubMed   |  Link to Article
Packer M, Coats AJ, Fowler MB,  et al; Carvedilol Prospective Randomized Cumulative Survival Study Group.  Effect of carvedilol on survival in severe chronic heart failure.  N Engl J Med. 2001;344(22):1651-1658
PubMed   |  Link to Article
Flather MD, Yusuf S, Køber L,  et al; ACE-Inhibitor Myocardial Infarction Collaborative Group.  Long-term ACE-inhibitor therapy in patients with heart failure or left-ventricular dysfunction: a systematic overview of data from individual patients.  Lancet. 2000;355(9215):1575-1581
PubMed   |  Link to Article
Bapoje SR, Bahia A, Hokanson JE,  et al.  The effects of mineralcorticoid receptor antagonists on the risk of sudden cardiac death in patients with left ventricular systolic dysfunction: a meta-analysis of randomized controlled trials.  Cir Heart Failhttp://circheartfailure.ahajournals.org/content/early/2013/02/12/CIRCHEARTFAILURE.112.000003.abstract.html. Accessed February 12, 2013
Hauptman PJ, Swindle JP, Masoudi FA, Burroughs TE. Underutilization of β-blockers in patients undergoing implantable cardioverter-defibrillator and cardiac resynchronization procedures.  Circ Cardiovasc Qual Outcomes. 2010;3(2):204-211
PubMed   |  Link to Article
Masoudi FA, Gross CP, Wang Y,  et al.  Adoption of spironolactone therapy for older patients with heart failure and left ventricular systolic dysfunction in the United States, 1998-2001.  Circulation. 2005;112(1):39-47
PubMed   |  Link to Article
Connolly SJ, Dorian P, Roberts RS,  et al; Optimal Pharmacological Therapy in Cardioverter Defibrillator Patients (OPTIC) Investigators.  Comparison of β-blockers, amiodarone plus β-blockers, or sotalol for prevention of shocks from implantable cardioverter defibrillators: the OPTIC Study: a randomized trial.  JAMA. 2006;295(2):165-171
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