Insomnia symptoms and heart rate recovery among patients in cardiac rehabilitation.

Insomnia symptoms (i.e., difficulty falling asleep, difficulty staying asleep, and early morning awakenings) are common among people with cardiovascular disease, and have been linked to adverse cardiovascular health outcomes. Reduced parasympathetic tone is one pathway through which risk may be conferred. The purpose of this study was to evaluate whether insomnia symptoms are associated with lower parasympathetic tone in cardiac rehabilitation patients with suspected insomnia. Participants (N = 121) completed a self-report measure of insomnia severity. 1-min heart rate recovery (HRR), an index of parasympathetic tone, was obtained during a maximal exercise test. Difficulty falling asleep, but not difficulty staying asleep or early awakenings, was associated with attenuated 1-min HRR. When analyses were restricted to participants with moderate and severe insomnia severity (n = 51), the strength of this association increased. In a sample of cardiac rehabilitation patients with insomnia, only the symptom of difficulty falling asleep was associated with lower parasympathetic tone, suggesting that individual insomnia symptoms may show specificity in their associations with physiological mechanisms.

Long-term Physical Activity Behavior After Completion of Traditional Versus Fast-track Cardiac Rehabilitation.

BACKGROUND: Despite the health benefits associated with regular physical activity (PA), many cardiac patients fail to maintain optimal levels of PA after completing cardiac rehabilitation (CR). The long-term impact of different CR delivery models on the PA habits of cardiac patients is not completely understood. OBJECTIVE: The purpose of this study is to use a multisensor accelerometer to compare the long-term impact of a traditional versus fast-track CR on the PA of patients with coronary artery disease 6 months after CR entry. METHODS: Forty-four participants attended either traditional (twice a week, 12 weeks; n = 24) or fast-track (once a week, 8 weeks; n = 20) CR. Exercise capacity (ie, 6-minute walk test distance) and PA were assessed at baseline and at 12 weeks and 6 months after CR entry. RESULTS: At 12 weeks, exercise capacity increased significantly in both groups and remained elevated by the 6-month follow-up. Sedentary time decreased from baseline to 12 weeks. However, at 6 months, it was comparable with the baseline level. There was no significant change in any other PA marker (ie, steps/day, time in light and moderate-vigorous PA) over the course of the study. CONCLUSIONS: Findings support the long-term effectiveness of CR on exercise capacity irrespective of the delivery model. However, participation in CR program, whether it be a traditional or fast-track CR exercise program, may not lead to long-term PA behavior change. Thus, CR participants may benefit from structured strategies that promote long-term PA adherence in addition to facilitating exercise capacity improvement.

Assessing agreement between population-level administrative pharmaceutical databases and patient-reported medication dispensation in cardiac rehabilitation patients.

BACKGROUND: Pharmacoepidemiology has emerged as a crucial field in evaluating the use and effects of medications in large populations to ensure their safe and effective use. This study aimed to assess the agreement of cardiac medication use between a provincial medication database, the Pharmaceutical Information Network (PIN), and reconciled medication data from confirmation through patient interviews for patients referred to cardiac rehabilitation. METHODS: The study included data from patients referred to the TotalCardiology Rehabilitation CR program, and medication data was available in both TotalCardiology Rehabilitation charts and PIN. The accuracy of medication data obtained from patient interviews was compared to that obtained from PIN with proportions and kappa statistics to evaluate the reliability of PIN data in assessing medication use. RESULTS: Patient-reported usage was higher for statins (41.6 %) vs. 38.4 %), ACE/ARB, beta-blockers (75.7 %) vs. 73.7 %), DOAC (3.5 %) vs. 2.6 %), and ADP-receptor antagonists (71.0 %) vs. 68.1 %) than if PIN was used. Patient-reported usage data was lower for Ezetimibe (4.7 vs. 4.8 %), Aldosterone antagonists (5.4 %) vs. 5.5 %), digoxin (0.9 %) vs. 1.0 %), calcium channel blockers (19.2 vs. 19.9 %) and warfarin (7.2 %) vs. 8.1 %). The results indicated that the differences between the two sources were very small, with an average agreement of 95.3 % and a kappa of 0.70. CONCLUSION: The study's results, which show a high level of agreement between PIN and patient self-reporting, affirm the reliability of PIN data as a source for obtaining an accurate assessment of medication use. This finding is crucial in the context of pharmacoepidemiology research, where the accuracy of data is paramount. Further research to explore the complementary use of both data sources will be valuable.

Cardiac rehabilitation attendance and outcomes in coronary artery disease patients.

BACKGROUND: Cardiac rehabilitation (CR) is an efficacious yet underused treatment for patients with coronary artery disease. The objective of this study was to determine the association between CR completion and mortality and resource use. METHODS AND RESULTS: We conducted a prospective cohort study of 5886 subjects (20.8% female; mean age, 60.6 years) who had undergone angiography and were referred for CR in Calgary, AB, Canada, between 1996 and 2009. Outcomes of interest included freedom from emergency room visits, hospitalization, and survival in CR completers versus noncompleters, adjusted for clinical covariates, treatment strategy, and coronary anatomy. Hazard ratios for events for CR completers versus noncompleters were also constructed. A propensity model was used to match completers to noncompleters on baseline characteristics, and each outcome was compared between propensity-matched groups. Of the subjects referred for CR, 2900 (49.3%) completed the program, and an additional 554 subjects started but did not complete CR. CR completion was associated with a lower risk of death, with an adjusted hazard ratio of 0.59 (95% confidence interval, 0.49-0.70). CR completion was also associated with a decreased risk of all-cause hospitalization (adjusted hazard ratio, 0.77; 95% confidence interval, 0.71-0.84) and cardiac hospitalization (adjusted hazard ratio, 0.68; 95% confidence interval, 0.55-0.83) but not with emergency room visits. Propensity-matched analysis demonstrated a persistent association between CR completion and reduced mortality. CONCLUSIONS: Among those coronary artery disease patients referred, CR completion is associated with improved survival and decreased hospitalization. There is a need to explore reasons for nonattendance and to test interventions to improve attendance after referral.

An observational study examining utilization of prehabilitation and its association with postoperative cardiac rehabilitation participation and risk factors following coronary artery bypass grafting.

BACKGROUND: Growing evidence supports the use of prehabilitation before coronary artery bypass grafting (CABG) to improve surgical outcomes, but its feasibility and impact on risk factor management in real-world clinical settings remain unknown. This observational study examined prehabilitation utilization and its association with postoperative cardiac rehabilitation (CR) participation and cardiovascular risk profile. METHODS: As standard care in a large Canadian city, eligible patients were referred to prehabilitation upon entering the elective CABG waitlist then were re-referred to CR following surgery. Prehabilitation consisted of medically supervised exercise training and multidisciplinary support with health behavior change until the scheduled surgery. An assessment of cardiorespiratory fitness, blood pressure, body habitus, psychological distress, lipids, glycated hemoglobin, and smoking status was completed during a prehabilitation intake visit then was repeated after surgery prior to starting CR. RESULTS: Among 97 prehabilitation referrals over a 20-month period, only 49% attended an intake visit. Most patients who enrolled (n = 39) also completed (n = 37) prehabilitation. Completion of prehabilitation was significantly associated with higher CR referral (OR = 6.92, 95% CI 1.50-32.00), enrollment (OR = 14.08, 95% CI 5.09-38.94) and attendance [t(62) = 4.48, p < .001], and with improvements in cardiorespiratory fitness, body mass index, and symptoms of depression and anxiety (p < .004). CONCLUSIONS: Prehabilitation may improve CR participation and risk factors among individuals undergoing elective CABG, but more work is needed to disseminate this service to eligible patients.

The impact of patient education on knowledge, attitudes, and cardiac rehabilitation attendance among patients with coronary artery disease.

OBJECTIVE: Patient education (PE) delivered during exercise-based cardiac rehabilitation (CR) aims to promote health behaviour change, including attendance at CR exercise sessions, by imparting knowledge about coronary artery disease (CAD) and improving CR-related attitudes. This study evaluated the impact of PE on aspects of patient motivation (i.e., CAD-related knowledge, attitudes towards CR) and exercise session attendance. METHODS: Adults with CAD referred to a 12-week CR program were recruited. CAD knowledge, perceived necessity/suitability of CR, exercise concerns, and barriers to CR were assessed pre/post-PE, and at 12-week follow-up. CR exercise attendance was obtained by chart review. RESULTS: Among 90 patients (60 ± 10 years; 88% men), CAD knowledge and perceived necessity of CR improved pre- to post-PE; gains persisted at 12-weeks. Stronger pre-CR intentions to attend exercise sessions predicted greater attendance. Greater knowledge gains did not predict improvements in CR attitudes or exercise attendance. CONCLUSION: Whereas PE may be useful for improving knowledge and attitudes regarding CAD self-management, more formative research is needed to determine whether PE can promote CR attendance. PRACTICE IMPLICATIONS: Cardiac PE programs may be more successful in promoting exercise attendance if they target patients' behavioural intentions to attend and attitudes toward CR, rather than focussing exclusively on imparting knowledge.

Bridging the intention-behavior gap for cardiac rehabilitation participation: the role of perceived barriers.

Purpose: Patients referred to cardiac rehabilitation after an acute coronary syndrome event commonly report strong intention to attend, but at least one-third do not participate. This study explored whether well-documented cardiac rehabilitation barriers (e.g., comorbidities, logistical/time constraints, and low social support) moderate the association between intention to participate and actual program enrollment and attendance.Method: Following referral but prior to commencing a 12-week outpatient cardiac rehabilitation program, 100 patients with acute coronary syndrome completed measures of intention to attend cardiac rehabilitation, perceived cardiac rehabilitation barriers, and social support. Program enrollment and attendance were determined by chart review.Results: Despite high reported intention to attend (M = 6.08/7.00, SD = 1.80), nearly one-in-five did not enroll. Weaker intention to attend (b = 0.46, SE = 0.16, p = 0.004) and greater cardiac rehabilitation barriers (b= -1.67, SE = 0.70, p = 0.017) corresponded to lower program enrollment. Similarly, weaker intention (b = 2.29, SE = 0.50, p < 0.001) and greater barriers (b =-6.19, SE = 1.55, p < 0.001) predicted poorer attendance. Barriers moderated the association between intention to participate and cardiac rehabilitation enrollment (b=-0.60, SE = 0.29, p = 0.037) and attendance (b = -3.12, SE = 1.02, p = 0.003).Conclusions: Perceived cardiac rehabilitation barriers influence whether patients successfully translate their intention to attend into actual program participation. Enhancing self-efficacy to overcome barriers may represent an important intervention target among prospective cardiac rehabilitation patients.Implications for RehabilitationPatients with acute coronary syndrome report strong intention to attend cardiac rehabilitation upon referral, yet cardiac rehabilitation programs remain underutilized.Assessing and addressing perceived barriers during the transition to cardiac rehabilitation, even when patients present as highly motivated to attend, may be critical to promoting program uptake.Rehabilitation professionals should ask patients about specific barriers to attending cardiac rehabilitation (e.g., financial constraints, transportation problems) and provide individualized solutions (e.g., fee subsidization, home- or web-based programs) to increase participation.

Predictive value of repeated versus single N-terminal pro B-type natriuretic peptide measurements early after-myocardial infarction.

BACKGROUND: A single, markedly elevated B-type natriuretic peptide (BNP) serum concentration predicts an increased risk of death after myocardial infarction (MI), though its sensitivity and predictive accuracy are low. We compared the predictive value of a modestly and persistently elevated, versus a single, markedly elevated measurement of N terminal pro-BNP (NT-BNP) early after MI. METHODS AND RESULTS: NT-BNP was measured 2-4, 6-10, and 14-18 weeks after MI. The median age of the 100 patients was 61 years, median left ventricular ejection fraction (LVEF) was 0.40, and 88% were males. Over a median follow-up of 39 months, 10 patients died. The initial median NT-BNP was 802 pg/mL and declined over time (P = 0.002). An initial NT-BNP > or =2,300 pg/mL (upper quintile) was observed in 19 patients and predicted a 3.4-fold higher independent risk of death (P = 0.05), with modest sensitivity (30%) and positive predictive accuracy (16%). A NT-BNP consistently > or =1,200 pg/mL (upper tertile) was observed in 19 patients, and was associated with a 5.7-fold higher independent risk of death (P = 0.01), with a higher sensitivity (50%) and positive predictive accuracy (26%) than a single, markedly elevated NT-BNP measurement. CONCLUSIONS: A moderately and persistently elevated NT-BNP in the early post-MI period was associated with a 5.7-fold higher risk of death, independent of age, LVEF, and functional class. Compared with a single measurement, serial NT-BNP measurements early after MI were more accurate predictors of risk of death.

A qualitative study exploring factors that influence enrollment in outpatient cardiac rehabilitation.

PURPOSE: This study explored patients' decision-making about whether or not to enroll in cardiac rehabilitation (CR), an underutilized program that is associated with significantly improved health outcomes. METHOD: Face-to-face interviews were conducted with acute coronary syndrome patients (n = 14) after referral to a local CR center, but prior to program enrollment. Thematic analysis was used to derive themes from interview transcripts. RESULTS: Three themes emerged including anticipated benefit, perceived ability, and contextual influences. Participants believed key benefits of CR would be access to specialist health care providers, improved longevity, reduced cardiovascular risk, as well as improved motivation, accountability, learning opportunities, and general fitness. Participants were concerned about their ability to engage in and travel to exercise sessions, pay the program fee, and manage scheduling conflicts. Contextual influences on decision-making included health care provider recommendation, first impressions of the CR center, knowledge gaps about what CR entails, input from family and peers, and psychological distress. CONCLUSION: The period following CR referral but prior to enrollment represents an optimal opportunity to promote in-the-moment decisions in favor of CR. Patients report both positive and negative aspects of CR, suggesting individualized efforts to resolve ambivalence may increase program participation. Implications for Rehabilitation Cardiovascular disease is a leading cause of mortality worldwide. Cardiac rehabilitation (CR) is an effective secondary prevention strategy to improve cardiovascular morbidity and mortality, but only a subset of eligible patients enroll. After referral but prior to enrollment, patients anticipate both positive and negative aspects of CR participation. Individualized efforts to resolve ambivalence, address knowledge gaps, and problem-solve barriers may increase uptake into CR programs.

The sustainability of exercise capacity changes in home versus center-based cardiac rehabilitation.

PURPOSE: Although participation in either center- or home-based cardiac rehabilitation (CR) can improve exercise capacity, the sustainability of this improvement following completion of the CR program is challenging. The purpose of this study was to compare the immediate and 1-year effectiveness of center- versus home-based CR on exercise capacity in cardiac patients who were given the choice of participating in a center-based or home-based CR program. METHODS: This was a retrospective study, which relied on the database from a large multidisciplinary CR program. A sample of 3488 cardiac patients participated either in center-based (n = 2803) or home-based (n = 685) CR. Participants underwent exercise testing at baseline, after 12 weeks of CR and again 1 year after completion of the CR programs. RESULTS: Following CR, exercise capacity (ie, peak metabolic equivalents [METs]) increased significantly in both groups (P < .05). From post-CR to the 1-year followup, exercise capacity remained unchanged in home-based CR participants (P = .183), whereas the center-based CR group demonstrated a decline in exercise capacity (P < .05). CONCLUSIONS: Although at the 1-year followup exercise capacity decreased in the center-based group, the observed decline did not seem to be clinically significant. The present findings indicate that when the patients were given a choice as to the delivery model (center- vs home-based) used for their CR program, they were relatively successful in retaining the improvement in exercise capacity 1 year post-CR irrespective of the exact location for their exercise training.

Cardiac rehabilitation referral, attendance and mortality in women.

BACKGROUND: Cardiac rehabilitation (CR) reduces mortality in women and men with coronary artery disease (CAD). The objective of this study was to examine sex differences in long-term mortality, based on CR referral rates and attendance patterns in a large CAD population. DESIGN: This is a retrospective cohort study. METHODS: The Alberta Provincial Project for Outcomes Assessment in Coronary Heart Disease (APPROACH) and Cardiac Wellness Institute of Calgary (CWIC) databases were used to obtain information on all patients. Rates of referral to and attendance at CR were compared by sex. Logistic regression models were constructed to assess whether sex predicted CR referral or completion. The association between referral, completion, and survival was assessed by sex using Cox proportional hazard models. RESULTS: 25,958 subjects (6374-24.6%-were women) with at least one vessel CAD were included. Females experienced reduced rates of CR referral (31.1% vs 42.2%, p < 0.0001) and completion (50.1 vs 60.4%, p < 0.0001). Adjusting for demographic and clinical characteristics, relative to men, CR referral was significantly lower in women (adjusted odds ratio (OR) 0.74, 95% CI 0.69, 0.79) as was CR completion (adjusted OR 0.73, 95% CI 0.66, 0.81). Women completing CR experienced the greatest reduction in mortality (HR 0.36, 95% CI 0.28, 0.45) with a relative benefit greater than men (HR 0.51, 95% CI 0.46, 0.56). CONCLUSION: This is the first large cohort study to demonstrate that referral to and attendance at CR is associated with a significant mortality reduction in women, comparatively better than that in men.

Obesity negatively impacts aerobic capacity improvements both acutely and 1-year following cardiac rehabilitation.

Cardiac rehabilitation (CR) produces a host of health benefits related to modifiable cardiovascular risk factors. The purpose of the present investigation was to determine the influence of body weight, assessed through BMI, on acute and long-term improvements in aerobic capacity following completion of CR. Three thousand nine hundred and ninety seven subjects with coronary artery disease (CAD) participated in a 12-week multidisciplinary CR program. Subjects underwent an exercise test to determine peak estimated metabolic equivalents (eMETs) and BMI assessment at baseline, immediately following CR completion and at 1-year follow-up. Normal weight subjects at 1-year follow-up demonstrated the greatest improvement in aerobic fitness and best retention of those gains (gain in peak METs: 0.95 ± 1.1, P < 0.001). Although the improvement was significant (P < 0.001), subjects who were initially classified as obese had the lowest aerobic capacity and poorest retention in CR fitness gains at 1-year follow-up (gain in peak eMETs: 0.69 ± 1.2). Subjects initially classified as overweight by BMI had a peak eMET improvement that was also significantly better (P < 0.05) than obese subjects at 1-year follow-up (gain in peak eMETs: 0.82 ± 1.1). Significant fitness gains, one of the primary beneficial outcomes of CR, can be obtained by all subjects irrespective of BMI classification. However, obese patients have poorer baseline fitness and are more likely to "give back" fitness gains in the long term. Obese CAD patients may therefore benefit from additional interventions to enhance the positive adaptations facilitated by CR.

Association of rate-controlled persistent atrial fibrillation with clinical outcome and ventricular remodelling in recipients of cardiac resynchronization therapy.

BACKGROUND: Whether patients with persistent atrial fibrillation (AF) obtain the same degree of benefit with cardiac resynchronization therapy (CRT) as those in sinus rhythm remains unclear. METHODS: We enrolled 93 patients undergoing CRT implantation, 20 (22%) of whom had rate-controlled persistent AF. The primary endpoint was CRT response defined as 1 class improvement in Specific Activity Scale and 15% reduction in left ventricular end-systolic volume (LVESV) during 12 months. Other endpoints included changes in 6-minute walk distance, quality of life, B-type natriuretic peptide, and survival. RESULTS: Baseline characteristics were similar in those with and without AF. Response to CRT was observed in 42% vs 54% of those with and without AF, respectively (P=0.3). Both groups had significant improvements in 6-minute walk distance, quality of life, and LVESV, but the improvement in LVESV was smaller in those with AF (13.7%±14.9% vs 27.7%±23.7%; P=0.02). During 2.8±1.4 years of follow-up, AF was associated with a 2.2-fold increased risk of death or transplantation (95% confidence interval, 1.2-3.9; P=0.01). CONCLUSIONS: Compared with patients without rate-controlled persistent AF, those with rate-controlled persistent AF had similar rates of clinical improvement but less left ventricular reverse remodelling in the first year after CRT. AF was associated with a markedly higher risk of death or transplantation in long-term follow-up. Given these findings, randomized studies assessing CRT efficacy in those with AF are warranted.

Attenuated recovery of heart rate turbulence early after myocardial infarction identifies patients at high risk for fatal or near-fatal arrhythmic events.

BACKGROUND: Autonomic dysfunction tends to improve over time after acute myocardial infarction (MI), but the clinical significance of autonomic remodeling is not well known. OBJECTIVE: The purpose of this study was to test the hypothesis that the amount of recovery of autonomic function early after MI is associated with a risk for serious arrhythmias. METHODS: The prognostic significance of autonomic remodeling after MI was assessed in one post-MI cohort [Cardiac Arrhythmia and Risk Stratification after Myocardial Infarction (CARISMA)] and validated in a second cohort [Risk Estimation After Infarction, Noninvasive Evaluation (REFINE)]. Changes in heart rate variability (DeltaHRV) and heart rate turbulence (DeltaHRT) were measured from 24-hour ECG recordings performed early (5-21 days) and later (6 weeks) after MI in CARISMA (n = 312). DeltaHRV and DeltaHRT were similarly measured from early (2-4 weeks) and later (10-14 weeks) post-MI recordings in REFINE (n = 322). RESULTS: HRV and HRT increased over time in both cohorts. Attenuated recovery of autonomic function, defined as DeltaHRT slope <2.0 ms/RR, was associated with a 9.4-fold (95% confidence interval 1.2-71.6; P = .03) higher risk of ECG-documented sustained ventricular tachycardia or ventricular fibrillation in CARISMA and a 7.0-fold (95% confidence interval 1.6-29.6; P = .009) higher risk of fatal or near-fatal events in REFINE. Changes in HRV and HRT were not predictive of nonarrhythmic death in either cohort. CONCLUSION: Attenuated recovery of autonomic function early after MI consistently predicts a higher risk of fatal or near-fatal arrhythmic events. A lack of improvement in HRT early after MI appears to be a specific marker for serious arrhythmic events.

Post-exercise assessment of cardiac repolarization alternans in patients with coronary artery disease using the modified moving average method.

OBJECTIVES: We sought to evaluate the utility of T-wave alternans (TWA) assessment in the immediate post-exercise period to identify and validate cutpoints for the modified moving average (MMA) assessment method. BACKGROUND: The presence of TWA is associated with an increased risk of cardiovascular death (CVD). The immediate post-exercise period, where increased physiologic stress and minimal surface artifact coexist, appears ideal to implement the MMA method. METHODS: A test (n = 322) and validation cohort (n = 681) provided 1,003 patients with coronary artery disease (CAD). We assessed TWA immediately after exercise. The outcomes, CVD and mortality, were adjudicated independent of the TWA results. RESULTS: During 48 months of follow-up 85 deaths, 54 categorized as CVD (64%), were observed. A linear relationship between the magnitude of TWA and the risk of CVD was identified. As a continuous measure TWA voltage was equivalent to ejection fraction in predicting the risk of CVD. To facilitate clinical application, a sensitive, modest predictive accuracy (20 microV) and a specific, greater predictive accuracy MMA cutpoint (60 microV) were identified and validated. Each cutpoint was associated with a 2.5-fold greater risk of CVD, independent of other important variables, including ejection fraction. CONCLUSIONS: Post-exercise assessment of TWA using the MMA method is a strong, independent predictor of risk in patients with CAD. The 20-microV cutpoint (87% sensitivity) appears to be most suitable in higher-risk patients, whereas the 60-microV cutpoint (95% specificity) appears more appropriate when TWA is used as a single screening test in those at lower risk. (Assessment of Noninvasive Methods to Identify Patients at Risk of Serious Arrhythmias After a Heart Attack; NCT00399503).

Noninvasive risk assessment early after a myocardial infarction the REFINE study.

OBJECTIVES: This study sought to determine whether combined assessment of autonomic tone plus cardiac electrical substrate identifies most patients at risk of serious events after myocardial infarction (MI) and to compare assessment at 2 to 4 weeks versus 10 to 14 weeks after MI. BACKGROUND: Methods to identify most patients at risk of serious events after MI are required. METHODS: Patients (n = 322) with an ejection fraction (EF) <0.50 in the initial week after MI were followed up for a median of 47 months. Serial assessment of autonomic tone, including heart rate turbulence (HRT), electrical substrate, including T-wave alternans (TWA), and EF was performed, interpreted blinded, and categorized using pre-specified cut-points where available. The primary outcome was cardiac death or resuscitated cardiac arrest. All-cause mortality and fatal or nonfatal cardiac arrest were secondary outcomes. RESULTS: Mean EF significantly increased over the initial 8 weeks after MI. Testing 2 to 4 weeks after MI did not reliably identify patients at risk, whereas testing at 10 to 14 weeks did. The 20% of patients with impaired HRT, abnormal exercise TWA, and an EF <0.50 beyond 8 weeks post-MI had a 5.2 (95% confidence interval [CI] 2.4 to 11.3, p < 0.001) higher adjusted risk of the primary outcome. This combination identified 52% of those at risk, with good positive (23%; 95% CI 17% to 26%) and negative (95%; 95% CI 93% to 97%) accuracy. Similar results were observed for the secondary outcomes. CONCLUSIONS: Impaired HRT, abnormal TWA, and an EF <0.50 beyond 8 weeks after MI reliably identify patients at risk of serious events. (Assessment of Noninvasive Methods to Identify Patients at Risk of Serious Arrhythmias After a Heart Attack; http://www.clinicaltrials.gov/ct/show/NCT00399503?order=1; NCT00399503).