Optimal Medical Therapy Use Among Patients Receiving Implantable Cardioverter/Defibrillators: Insights From the National Cardiovascular Data Registry FREE

Current guidelines predicate primary prevention cardioverter/defibrillator (ICD) implantation on patients receiving “optimal medical therapy” (OMT), defined as use of both β-blocker and angiotensin-converting enzyme inhibitor or angiotensin receptor blocker (ACEI/ARB) in the absence of contraindications.¹ These recommendations promote clinical optimization of patients with low left ventricular ejection fraction (LVEF) as well as cost-effective allocation of high-cost device therapy. While prior studies hint at significant care gaps among select ICD recipients,² the ICD Registry offered the opportunity to examine national patterns of OMT use among first-time ICD recipients in contemporary, real-world practice.

Details regarding the ICD Registry, including data definitions and quality, have been published previously.^3- 4 Among 1201 centers reporting data on consecutive ICD procedures from January 1, 2007, to June 30, 2009, we examined 175 757 patients undergoing first-time ICD implantation and excluded those younger than 18 years, who had an LVEF higher than 35%, or who had in-hospital death or unknown OMT status. Patients enrolled in a study necessitating blinding or with documented contraindications to β-blocker or ACEI/ARB use were counted toward medication use. Patients' clinical and procedural characteristics and implanting physician and hospital characteristics were compared among patients stratified by OMT use. Multivariable hierarchical logistic regression modeling using backward variable selection (P < .01) examined factors associated with OMT, β-blocker, and ACEI/ARB use. Missing values were imputed (continuous variables to the median; categorical to the mode).

Among 175 757 initial ICD recipients with an LVEF of 35% or lower, 45 240 (25.7%) were eligible for but did not receive OMT. Similar rates were observed when ICD placement was the primary purpose of hospitalization (24.6%) and among primary prevention ICD recipients (25.6%). The rate of OMT prescription by site ranged from 0% to 100%, with a median of 73.5% (interquartile range, 64%-82%). Patients receiving OMT were more likely to be younger, have commercial insurance, and have a diagnosis of hypertension and were less likely to have a history of ischemic heart disease, recent heart failure hospitalization, atrioventricular node conduction abnormalities, or renal dysfunction (eTable 1). Among patients who underwent coronary artery bypass graft during the hospitalization (n = 2632), 65.7% were discharged on OMT, whereas 75.3% of patients (n = 5258) who underwent percutaneous coronary intervention during the hospitalization were discharged receiving OMT. Higher OMT rates were observed for implanting physicians with formal electrophysiology training (eTable 2). Use of OMT was highest at government hospitals (78.5%) and lowest at private and/or community hospitals (73.7%; P < .001; eTable 2). Teaching hospitals had a higher rate of OMT use (76.0% vs 72.3%]] P < .001).

In multivariate analysis (Figure), factors associated with higher OMT use included treatment at a teaching hospital (odds ratio [OR], 1.16; 95% CI, 1.06-1.27), percutaneous coronary intervention during the admission (OR, 1.11; 95% CI, 1.04-1.19]), history of hypertension (OR, 1.32; 95% CI, 1.28-1.36), and a cardiovascular indication for admission (OR, 1.11; 95% CI, 1.04-1.19). Factors associated with the lowest odds of OMT use were coronary artery bypass graft during the admission (OR, 0.66; 95% CI, 0.61-0.72) and an implanting care provider who was board certified in surgery (OR, 0.73; 95% CI, 0.66-0.80). Other factors associated with low OMT rates included medical comorbidities (renal dysfunction, chronic lung disease, and cerebrovascular disease), severity of cardiovascular disease (atrial or ventricular tachyarrhythmias, conduction abnormalities, New York Heart Association class IV heart failure), and patient sex and age.

An ACEI/ARB was not prescribed in 18.7% of patients with low LVEF in the absence of documented contraindications, and 10.7% were not prescribed a β-blocker. The lowest odds for ACEI/ARB use were observed for coronary artery bypass graft during the index admission (OR, 0.59; 95% CI, 0.54-0.65) and surgical training of the performing operator (OR, 0.76; 95% CI, 0.68-0.84; eTable 3). The lowest ORs for β-blocker use were for chronic lung disease (OR, 0.72; 95% CI, 0.70-0.75) and surgical training of the performing operator (OR, 0.74; 95% CI, 0.65-0.84). Despite ICD implantation, patients with abnormal atrioventricular node conduction were also less likely to receive β-blockers.

Although medical therapy optimization reduces mortality,¹ the risks of heart failure decompensation⁵ and ventricular arrhythmias requiring shocks,⁶ 1 in 4 ICD recipients with an LVEF of 35% or lower are not prescribed β-blockers and ACEI/ARBs.¹

The in-hospital “snapshot” captured by the ICD Registry highlights a critical window of opportunity for therapy optimization for patients with low LVEF. Among patient and health care provider variables, surgical revascularization and ICD implantation by a board-certified surgeon were 2 of the strongest factors independently associated with lower OMT use. Although hemodynamic factors may play a role, persistently lower utilization rates of other evidence-based therapies (eg, statins and antiplatelet agents) among surgical patients⁷ suggest that the care provider's training background may influence prescribing patterns. In addition, nonelectrophysiologists are more likely to implant non–evidence-based ICDs and to miss candidates for resynchronization therapy.^3- 4 These data suggest that patients implanted by nonelectrophysiology care providers may benefit from further scrutiny to maximize guidelines adherence.

In the Registry to Improve the Use of Evidence-Based Heart Failure Therapies in the Outpatient Setting (IMPROVE-HF), failure to document was a significant contributor to failure to treat.⁸ While our study cannot distinguish between true but undocumented contraindications in patients and health care provider reluctance to challenge patients deemed at risk of developing an adverse reaction, it underscores the need for increased vigilance for treatment opportunities. For example, the association of atrioventricular conduction abnormalities with failure to receive a β-blocker suggests that the elimination of this contraindication by ICD implantation was ignored. Electronic decision support and standardized discharge order sets may improve guideline adherence but cannot completely close care gaps.⁹ Direct involvement of a medical cardiologist in the peri-implantation setting may help identify appropriate, medically optimized ICD candidates as well as maximize OMT adherence after implantation.

From a broader perspective, the observed low rate of OMT use supports the need for increased focus on this aspect of care for patients receiving ICD therapy. Institutional rates of medical therapy for patients undergoing ICD implantation are currently available to hospitals from the National Cardiovascular Data Registry, but this study suggests that those data are not yet driving practice improvement. These findings suggest that further investigation is needed to identify quality improvement and reporting strategies that effectively reduce care gaps such as those identified in this study.

In conclusion, despite well-proven benefits and guideline recommendations, gaps in medical therapy optimization of ICD recipients persist. These results underscore the need for dedicated strategies, optimized quality of care, and improved cost-effectiveness of care for patients with heart failure.