Acute Coronary Syndrome:  What Do Patients Know? FREE

Although knowledge about heart disease and its symptoms is not sufficient to reduce delay in seeking treatment, it is necessary for patients to have this information so that they can quickly identify symptoms of acute coronary syndrome (ACS) and take prompt action to seek care. A decision to seek care quickly is critical to minimizing morbidity and mortality in ACS.^1- 4 In fact, the goal for instituting definitive treatment in an evolving acute myocardial infarction (AMI) is 1 hour from symptom onset,⁵ with survival rates improved by up to 50% if reperfusion is achieved within 1 hour.⁵ Delaying treatment even by 30 minutes reduces the mean life expectancy by 1 year,⁶ underscoring the importance of patients knowing the nature of ACS symptoms and seeking care quickly. The median time from symptom onset to admission to the hospital is 2.5 to 3.0 hours, and this delay has not changed substantially for the past decade, despite extensive community education programs.^7- 8

Barriers to seeking appropriate care quickly are both cognitive and emotional.^9- 11 If patients do not know symptoms of ACS, such as nausea, jaw pain, and syncope, as well as the more commonly associated symptoms, such as chest and left arm pain, they will not label their physical symptoms appropriately. If they do not perceive themselves as vulnerable or at risk for experiencing AMI, they will seek another explanation for their new symptoms. Thus, a lack of knowledge about cardiac symptoms and low perception of risk can contribute to the prolonged delay seen in many cases of ACS. It is important to determine what patients with coronary heart disease know about the symptoms of their disease and the appropriate course of action to take, as well as their level of perceived risk for a future cardiac event to provide appropriate information during the brief encounter available to most physicians and to design appropriate educational programs. Therefore, we conducted a study to assess the level of knowledge about heart disease and ACS symptoms in patients with documented ischemic heart disease who were at high risk for a future cardiac event. We also identified the characteristics of those patients who had inadequate knowledge about cardiac symptoms and treatment options, as well as those who identified themselves as having a low risk for a future ACS event.

Following review and approval of the study by the institutional review boards at the participating institutions, we enrolled 3522 patients with diagnosed ischemic heart disease into a randomized controlled trial. The study design has been described previously¹²; briefly, it consisted of randomization to a single educational session delivered face-to-face by a nurse or to a care-as-usual control group. The hypothesis of the trial was that the experimental intervention would decrease prehospital delay time (from ACS symptom onset to hospital admission) and increase ambulance use and appropriate use of aspirin. The current analysis focuses on the knowledge of cardiac patients and their perceived risk for a future AMI measured prior to group assignment.

Patients were recruited from participating centers' cardiovascular in-patient units and coronary catheterization laboratories and from a variety of out-patient cardiac clinics, cardiac rehabilitation programs, and community medical practices in the United States, Australia, and New Zealand. When allowed by the appropriate institutional review boards, eligible patients were sent a letter signed by their private physician inviting them to participate and giving them a toll-free telephone number to call. Subjects were eligible if they had a confirmed diagnosis of ischemic heart disease and if they lived independently (ie, not in an institutional setting). No attempt was made to categorize a patient's condition as being either acute or chronic because complete medical records were not always available at the time of enrollment. The diagnosis of ischemic heart disease was confirmed by medical record review, either of hospital medical records in the case of those patients currently or recently hospitalized, or medical records maintained in the offices of private physicians if patients were referred by a medical practice. Subjects were excluded if they had (1) an untreated malignant neoplasm or neurological disorder with impaired cognition, (2) an inability to read or understand English, and (3) a major and uncorrected hearing loss. The latter 2 criteria were assessed by the research assistant in the first face-to-face meeting.

All participants gave informed consent prior to randomization. Baseline data were collected by medical record review, patient interview, and written questionnaires. Instruments were administered in a place convenient to the patient (eg, out-patient clinic, physician's office, or patient's home). Data collected from the medical record and interview included sociodemographic information, clinical history, and the specialty of the treating physician. Data regarding patients' knowledge about cardiovascular disease and ACS symptoms, as well as their perceived vulnerability for a future AMI, were collected using a structured questionnaire. The interviewers were registered nurses with graduate degrees and special expertise in cardiac care. Project directors at each study site audited 10% of all enrollments.

Knowledge was measured by the Knowledge Scale of the ACS Response Index, a modification of the instrument developed for the Rapid Early Reaction for Coronary Treatment (REACT) study¹³ to measure knowledge, attitudes, and beliefs about coronary heart disease. Content validity, discriminant validity, and internal consistency reliability were assessed and demonstrated for scales measuring knowledge, attitudes, and beliefs using established methods.¹⁴ The knowledge scale consists of 21 items in which patients were asked to identify possible AMI symptoms from a list of 15 correct and 6 incorrect symptoms. Patients were also asked to respond to 5 additional items about heart disease that were framed as statements with true/false responses. Examples are “Hospitals have drugs that reduce the damage done when a heart attack occurs” and “Heart disease is the most common cause of death in women in the United States.” The instrument was self-administered. Internal reliability of the knowledge scale was measured by Cronbach α and was judged adequate at 0.76.

Perceived vulnerability to a future ACS event was measured by the following question: “Compared with other people your age, how likely do you think it is that you could have a heart attack in the next 5 years?” Participants were asked to respond to the statement using a 5-point Likert scale that ranged from 1 (much less likely) to 5 (much more likely).

We used SPSS statistical software (version 15.0 for Windows; SPSS Inc, Chicago, Illinois) for data analysis, and accuracy of data entry was checked by systematic audits, as well as by examining the data to identify outliers and missing data. The χ² test was used to examine categorical data, and the independent t test was used to test continuous data in relation to the high and low knowledge groups and the high and low perceived risk groups. There was no notable difference in knowledge or risk perception scores between patients recruited from the United States compared with patients from Australia or New Zealand, so the sample was combined for all analyses. Logistic regression analyses were performed to identify predictors of high knowledge (>70% of answers were correct on the Knowledge Scale of the ACS Response Index, with 70% set as a common demarcation of failure on educational tests) and high perceived risk group membership (based on a response that the patient perceived the risk of a heart attack in the next 5 years as greater than or equal to that of an age-matched healthy control). Variables showing marginal association with P < .25 in univariate analyses were forwarded to the regression analysis. The Hosmer-Lemeshow statistic was used to evaluate goodness-of-fit of the model. Except where otherwise specified, the level of significance for statistical analyses was set at P < .05.

The mean (SD) age of the patients was 67 (11) years, 68% were male, and all had documented ischemic heart disease (Table 1). Despite having a history of coronary heart disease, 44% of patients had substantial gaps in knowledge about ACS, as documented by scores of less than 70% on the Knowledge Scale of the ACS Response Index. The mean (SD) cardiac knowledge score for the entire sample on the ACS Response Index was 71% (12%) (range, 8%-100%). Characteristics associated with higher knowledge scores were female sex, participation in a formal cardiac rehabilitation program, higher levels of education, younger age, and medical care by a cardiologist (compared with care by a family practitioner or internist) as summarized in Table 2. Clinical history, such as previous AMI, cardiac surgery, or percutaneous coronary intervention, made no notable difference in knowledge level. Documented cardiac risk factors (ie, being a current smoker [P  = .76] or having hypercholesterolemia [P  = .70]) were also not significant predictors of knowledge about ACS (see Table 2 for P values).

Sex is an important predictor of clinical outcome in ACS, with women having higher mortality following AMI^14- 15 and longer prehospital delay to treatment of an ACS than men.¹⁶ Given that one of the most powerful predictors of knowledge in our sample was sex, with women significantly more likely to have a score of at least 70% on the Knowledge Scale than men (odds ratio, 1.77; P < .001), we further examined differences between men and women in cardiac knowledge. Overall knowledge scores were higher for women than men (73% vs 70%). Women more accurately identified less-typical symptoms of AMI than men (back pain, jaw pain, heartburn, nausea, and neck pain). Fewer men than women knew that heart disease was the most common cause of death in women. More men than women stated their preference for someone to drive them to the hospital if they experienced AMI symptoms rather than go by ambulance (Table 3).

In this group of patients, who were all at high risk for a future AMI, 43% inappropriately assessed their risk as less than or the same as other people their age. More men than women perceived themselves as being at low risk (47% vs 36%, respectively). Yet, men were significantly more confident that they would recognize signs or symptoms of an AMI in themselves or others compared with women (P  = .001), despite the fact that they knew less about symptoms of AMI than women. Patients were most likely to identify themselves as “low risk” for a future AMI in the next 5 years if they had undergone coronary bypass surgery (P  = .003) or were younger in age (P  = .003). Patients who were female (P  = .001), had higher scores on the Knowledge Scale (P  = .001), were current smokers (P  = .02), had a history of AMI or angioplasty (P  = .001), and had hypercholesterolemia (P  = .03) were significantly less likely to describe themselves as being at low risk for a future AMI. Patients were not significantly different in their assessment of risk by virtue of their participation in cardiac rehabilitation, receiving care from a cardiologist rather than an internist, or having a higher level of formal education (see Table 4 for P values). We evaluated patients' attitudes about calling the emergency medical system (EMS) when experiencing symptoms of ACS; 69% said they would call the EMS, whereas 31% would choose private transportation.

Where do patients who are diagnosed as having ACS obtain their health information? In decades past, such patients were frequently hospitalized and would receive education and counseling from physicians and nurses during their hospital stay. Unfortunately, structural changes in health care delivery have led to decreased lengths of hospital stay and increased use of outpatient facilities for cardiac diagnosis and treatment, which in turn have had a dramatic effect on the time available for the education of patients with ACS. In a recent study of the discharge education given to patients with heart failure, only 54% had received the instructions comprising the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) process-of-care measure.¹⁷ This percentage was achieved given the impetus of JCAHO standards, and it is likely that the percentage for premandated discharge education is much lower. Thus, there is an increasing onus on physicians to ensure that patients who are at high risk for a future AMI are knowledgeable about ACS symptom presentation and that these patients understand the importance of responding quickly to cardiac symptoms to optimize survival and treatment outcomes.

To our knowledge, our study is the first large-scale, international study conducted to assess the knowledge of patients with documented ACS about their disease and its symptoms. Given that individuals with coronary heart disease have a 5 to 7 times greater risk of AMI or death than the general population,¹⁸ we also assessed their sense of perceived risk for a future AMI with the assumption that a heightened sense of perceived risk may contribute to quicker action to seek treatment at the onset of symptoms and reduced prehospital delay time. Physicians and other health professionals might appropriately believe that this group of high-risk patients will be knowledgeable about the actions to take in the face of new ACS symptoms and will act quickly to access the EMS. However, numerous investigators^7,19 have documented that patients who have experienced an AMI in the past have prehospital delay times that are not markedly different than patients with no history of AMI. Given the relatively low level of knowledge in this high-risk population, it is perhaps not surprising that persons with a history of AMI are not more likely to recognize AMI symptoms and seek treatment early when compared with previously healthy individuals.¹⁹

Our findings about what patients with documented heart disease know about the symptoms of AMI and appropriate actions to take, as well as their perceived risk of vulnerability for a future AMI, provide important insights into this phenomenon that is counterintuitive for physicians. Patients' knowledge about heart disease was relatively low and perceptions of personal risk lower than expected in this high-risk group with a history of heart disease. In an attempt to identify which patients in clinical practice may need extra attention by physicians in medical follow-up visits, we identified characteristics associated with higher and lower levels of knowledge about heart disease. Sex, age, and education were all significant predictors of knowledge, with male sex, older age, and less formal education associated with less knowledge (see Table 4 for P values).

The findings about sex were particularly surprising because women have often underestimated their risk for heart disease in years past^20- 21 and have had longer prehospital delay times than men,^22- 23 suggesting a lack of knowledge about AMI symptoms or a lack of appreciation for the importance of heart disease as a cause of death in women. In recent large community samples of healthy individuals, sex made no difference in knowledge about heart disease and its symptoms,^24- 25 findings that are in direct contrast to those in the current study. In our study, which included only people with known coronary artery disease, we found that women were more knowledgeable than men about ACS symptoms and more likely to see themselves at higher risk than age-matched healthy controls.

The findings related to sex differences suggest that physician counseling of female patients, coupled with a number of community-based, public education programs conducted over the past decade by the federal government and organizations, such as the American Heart Association and the National Heart Foundation of Australia, have had a positive effect. Some of the campaigns, such as the American Heart Association's “Go Red” and the National Heart, Lung, and Blood Institute's “Heart Truth” campaign, have focused specifically on women to alert them to their risk for heart disease, and our findings support prior evidence that such campaigns have had a positive effect.²¹ We found that women were more likely than men to identify less well appreciated symptoms of AMI and were more likely to identify the appropriate actions to take in the face of new AMI symptoms. Compared with men, women were significantly more likely to know about the possibility of reperfusion therapy and the need to call the EMS rather than drive themselves to the hospital (see Table 3 for P values). Other investigators have found that most information for women about ACS symptoms comes from the media,²⁵ suggesting that the recent media campaigns have been successful in raising women's level of knowledge and sense of perceived risk.

Two other clinical variables were associated with higher levels of knowledge; namely, being under the care of a cardiologist and having attended a cardiac rehabilitation program. Both underscore the importance of specialty care for patients with heart disease, findings that are well supported in previous studies of clinical outcomes. For example, patients with heart disease who are seen by cardiologists rather than generalists for their care are more likely to receive care recommended in clinical guidelines and more likely to have positive clinical outcomes.²⁶

Although not yet documented to our knowledge, a perceived sense of vulnerability to a future AMI may be helpful in getting patients to pay attention to cardiac symptoms when they occur and to seek treatment promptly by calling the EMS. Patients were more likely to feel at appropriately high risk if they were older, a current smoker, and had a history of AMI, angioplasty, or hypercholesterolemia, which are highly accurate perceptions given epidemiological data about cardiac risk factors. Higher levels of knowledge were also associated with higher levels of perceived risk, suggesting that instruction about ACS symptoms and steps to take in an emergency may influence patients' understanding of their vulnerability for a future heart attack. This inverse relationship of knowledge and perceived risk suggests that the lower levels of knowledge about ACS documented in men compared with women underscores the need for continuing reinforcement of the information in physician-patient encounters. A sense of perceived risk or vulnerability may decrease prehospital delay to treatment, although this association awaits further study.

In summary, knowledge about ACS symptoms and correct actions to take in seeking care is required for appropriate self-care. Physicians can identify patients who are less likely to have necessary knowledge and an appreciation of their high-risk status and provide extra education and counseling. Our findings suggest that men, elderly individuals, those with low levels of education, and those who have not attended a cardiac rehabilitation program are more likely to require special efforts during medical office visits to review symptoms of AMI and to learn the appropriate actions to take in the face of new symptoms of ACS.

Correspondence: Kathleen Dracup, DNSc, University of California, San Francisco, School of Nursing, 2 Koret Way, Room 319 C, San Francisco, CA 94143 (Kathy.Dracup@nursing.ucsf.edu).

Accepted for Publication: November 18, 2007.

Author Affiliations: School of Nursing, University of California, San Francisco (Drs Dracup and Paul); Critical Care Nursing Professorial Unit, Northern Sydney Central Coast Health and University of Technology Sydney, Sydney, Australia (DrMcKinley and Ms Marshall); School of Nursing, University of California, Los Angeles (Drs Doering and Cross); School of Nursing, University of Pennsylvania, Philadelphia (Dr Riegel); Department of Health Services, University of Washington, Seattle (Dr Meischke); School of Nursing, University of Kentucky, Lexington (Dr Moser); School of Nursing, University of Nevada, Reno (DrPelter); Sharpe HealthCare, San Diego, California (Ms Carlson); and Research Centre for Clinical and Community Practice Innovation, Griffith University, Brisbane, Australia (Dr Aitken).

Author Contributions: Dr Dracup had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Dracup, McKinley, Doering, Riegel, Meischke, and Moser. Acquisition of data: Dracup, McKinley, Meischke, Moser, Carlson, Aitken, Marshall, and Cross. Analysis and interpretation of data: Dracup, McKinley, Riegel, Moser, Pelter, and Paul. Drafting of the manuscript: Dracup, Doering, Riegel, and Moser. Critical revision of the manuscript for important intellectual content: Dracup, McKinley, Meischke, Moser, Pelter, Aitken, Marshall, Cross, and Paul. Statistical analysis: Dracup, Doering, Riegel, and Paul. Obtained funding: Dracup, McKinley, and Meischke. Administrative, technical, and material support: McKinley, Riegel, Pelter, Carlson, Aitken, and Marshall. Study supervision: Dracup, McKinley, Moser, Carlson, and Cross.

Financial Disclosure: None reported.

Funding/Support: Funding was provided by the National Institute of Nursing Research, National Institutes of Health grant R01-NR07952.