Effectiveness of the implantable cardioverter defibrillator in blacks versus whites (from MADIT-II)

Racial and ethnic differences in implantable cardioverter-defibrillator patient selection, management, and outcomes

Racial and ethnic differences in treatment-cardiovascular and otherwise-have been documented in many aspects of the American health care system and can be seen in implantable cardioverter-defibrillator (ICD) patient selection, counseling, and management. ICDs have been demonstrated to be a powerful tool in the prevention of sudden cardiac death, yet uptake across all eligible patients has been modest. Although patients who do not identify as White are disproportionately eligible for ICDs in the United States, they are less likely to see specialists, be counseled on ICDs, and ultimately have an ICD implanted. This review explores racial and ethnic differences demonstrated in ICD patient selection, outcomes including shock effectiveness, and postimplantation monitoring for both primary and secondary prevention devices. It also highlights barriers for uptake at the health system, physician, and patient levels and suggests areas of further research needed to clarify the differences, illuminate the driving forces of these differences, and investigate strategies to address them.

Racial Disparities in Ion Channelopathies and Inherited Cardiovascular Diseases Associated With Sudden Cardiac Death

Cardiovascular disease (CVD) continues to be the most common cause of death worldwide, and cardiac arrhythmias account for approximately one half of these deaths. The morbidity and mortality from CVD have been reduced significantly over the past few decades; however, disparities in racial or ethnic populations still exist. This review is based on available literature to date and focuses on known cardiac channelopathies and other inherited disorders associated with sudden cardiac death in African American/Black subjects and the role of epigenetics in phenotypic manifestations of CVD, and illustrates existing disparities in treatment and outcomes. The review also highlights the knowledge gaps that limit understanding of the manifestation of phenotypic abnormalities across racial or ethnic groups and discusses disparities associated with device underuse in the management of patients at risk for sudden cardiac death. We discuss factors related to reports in the United States, that the overall mortality attributed to CVD and the number of out‐of‐hospital cardiac arrests are higher among African American/Black subjects when compared with other racial or ethnic groups. African American/Black subjects are disproportionally affected by CVD, including cardiac arrhythmias and sudden cardiac death, thus highlighting a major concern in this population that remains underrepresented in clinical trials with limited genetic testing and device underuse. The proposed solutions include (1) early identification of genetic variants, which is crucial in tailoring a preventive management strategy; (2) inclusion of diverse racial or ethnic groups in clinical trials; (3) compliance with guideline‐directed medical treatment and referral to cardiovascular subspecialists; and (4) training and mentoring of underrepresented junior faculty in cardiovascular health disparities research.

Race, ethnicity, and the risk of sudden death<sup/>

Sudden cardiac death (SCD) is a major cause of death worldwide, with an estimated U.S. annual incidence of 350,000 [1]. This review will examine the influence of race and ethnicity on SCD burden and risk factors, and review the available literature on resuscitation outcomes and primary prevention of SCD. An improved understanding of associations between race, ethnicity, and SCD may provide clues to mechanisms, lead to improved prevention of SCD, and ultimately reduce racial and ethnic disparities in the burden of SCD.

Cardiac resynchronization therapy: A comparative analysis of mortality in African Americans and Caucasians

BACKGROUND

Cardiac resynchronization therapy (CRT) is recommended in patients with heart failure, reduced left ventricular ejection fraction, and a prolonged QRS duration. African Americans are underrepresented in clinical trials and CRT is underutilized; consequently, the benefits and outcomes of CRT are not well-defined.

METHODS

We evaluated 294 patients, determined survival using Kaplan-Meier analysis, and used Cox proportional hazards regression model to determine predictors of mortality. Propensity score-match analysis was applied to balance covariates in African Americans and Caucasians.

RESULTS

The mean age for African Americans (n  =  131) and Caucasians (n  =  163) was 65 ± 12 and 70 ± 13 years (P  =  0.0003). Mortality in African Americans was 28% compared to 37% in Caucasians (P  =  0.14) over a median follow-up of 8.1 ± 0.6 years. Survival was significantly reduced in African Americans and Caucasians with a glomerular filtration rate (GFR) < 60 (6.7 ± 0.4, 95% confidence interval [CI]: 5.9-7.5 vs 8.6 ± 0.5 CI: 7.7-9.5 years, P  =  0.005), and those not treated with an aldosterone antagonist (7.1 ± 0.4, 95% CI: 6.5-7.9 vs 8.7 ± 0.6, 7.6-9.9 years, P  =  0.04), respectively. Independent predictors of mortality were a GFR <60 and low left ventricular ejection fraction. In African Americans, ischemic cardiomyopathy (ICM) and lack of therapy with an angiotensin-converting enzyme inhibitor (ACEI) or angiotensin II receptor blocker (ARB) were associated with increased mortality.

CONCLUSIONS

Long-term survival benefit from CRT was similar in African Americans and Caucasians. A GFR < 60 and lack of therapy with an aldosterone antagonist were associated with decreased survival. Survival also was inversely related to the number of comorbidities. In African Americans, underutilization of an ACEI or ARB, and ICM were additional factors associated with increased mortality.

Representation of black patients in randomized clinical trials of heart failure with reduced ejection fraction

BACKGROUND

Black individuals have a disproportionately higher burden of heart failure with reduced ejection fraction (HFrEF) relative to other racial and ethnic populations. We conducted a systematic review to determine the representation, enrollment trends, and outcomes of black patients in historic and contemporary randomized clinical trials (RCTs) for HFrEF.

METHODS

We searched PubMed and Embase for RCTs of patients with chronic HFrEF that evaluated therapies that significantly improved clinical outcomes. We extracted trial characteristics and compared them by trial type. Linear regression was used to assess trends in enrollment among HFrEF RCTs over time.

RESULTS

A total of 25 RCTs, 19 for pharmacotherapies and 6 (n=9,501) for implantable cardioverter defibrillators, were included in this analysis. Among these studies, there were 78,816 patients, 4,640 black (5.9%), and the median black participation per trial was 162 patients. Black race was reported in the manuscript of 14 (56.0%) trials, and outcomes by race were available for 12 (48.0%) trials. Implantable cardiac defibrillator trials enrolled a greater percentage of black patients than pharmacotherapy trials (7.1% vs 5.7%). Overall, patient enrollment among the 25 RCTs increased over time (P = .075); however, the percentage of black patients has decreased (P = .001). Outcomes varied significantly between black and white patients in 6 studies.

CONCLUSIONS

Black patients are modestly represented among pivotal RCTs of individuals with HFrEF for both pharmacotherapies and implantable cardioverter defibrillators. The current trend for decreasing black representation in trials of HF therapeutics is concerning and must improve to ensure the generalizability for this vulnerable population.

Comparative Efficacy of Cardiac Resynchronization Therapy in Africans Americans Compared With European Americans

Race has seldomly been reported in the major clinical trials of cardiac resynchronization therapy (CRT). When described, African Americans (AAs) were substantially under-represented. This study sought to compare reverse ventricular remodeling and long-term outcomes in AAs versus European Americans (EAs) with advanced heart failure who underwent CRT. We extracted demographic (including race), clinical, and echocardiographic data on patients with advanced heart failure who underwent CRT with a left ventricular ejection fraction (LVEF) ≤35% and a QRS duration ≥120 ms. Long-term outcomes were compared between AAs and EAs. In patients in whom follow-up echocardiograms were available, improvement in LVEF (defined as an absolute improvement ≥5%) was compared between races. From a cohort of 662 patients, there were 88 AAs and 574 EAs. At a mean follow-up of 5.0 ± 2.5 years, survival rate free of left ventricular assist device (LVAD) and heart transplant was 54.5% for AAs and 53.8% for EAs (log-rank p = 0.997). In multivariate analysis, there was no difference in survival free of heart transplant or LVAD based on race (hazard ratio 1.1 [0.74 to 1.56], p = 0.72, EAs race as referent); 424 patients had a follow-up echocardiogram (55.4% EAs and 64.7% AAs). In multivariate analysis, there was no difference in the incidence of response based on race (1.1 [0.6 to 2.1, p = 0.80], EAs as referent). AAs derive similar benefits with CRT compared with EAs in terms of improvement in LVEF and long-term survival free of LVAD and heart transplant.

Primary prevention implantable cardioverter-defibrillators in older racial and ethnic minority patients

BACKGROUND

Racial and ethnic minorities are under-represented in clinical trials of primary prevention implantable cardioverter-defibrillators (ICDs). This analysis investigates the association between primary prevention ICDs and mortality among Medicare, racial/ethnic minority patients.

METHODS AND RESULTS

Data from Get With The Guidelines-Heart Failure Registry and National Cardiovascular Data Registry's ICD Registry were used to perform an adjusted comparative effectiveness analysis of primary prevention ICDs in Medicare, racial/ethnic minority patients (nonwhite race or Hispanic ethnicity). Mortality data were obtained from the Medicare denominator file. The relationship of ICD with survival was compared between minority and white non-Hispanic patients. Our analysis included 852 minority patients, 426 ICD and 426 matched non-ICD patients, and 2070 white non-Hispanic patients (1035 ICD and 1035 matched non-ICD patients). Median follow-up was 3.1 years. Median age was 73 years, and median ejection fraction was 23%. Adjusted 3-year mortality rates for minority ICD and non-ICD patients were 44.9% (95% confidence interval [CI], 44.2%-45.7%) and 54.3% (95% CI, 53.4%-55.1%), respectively (adjusted hazard ratio, 0.79; 95% CI, 0.63-0.98; P=0.034). White non-Hispanic patients receiving an ICD had lower adjusted 3-year mortality rates of 47.8% (95% CI, 47.3%-48.3%) compared with 57.3% (95% CI, 56.8%-57.9%) for those with no ICD (adjusted hazard ratio, 0.75; 95% CI, 0.67%-0.83%; P<0.0001). There was no significant interaction between race/ethnicity and lower mortality risk with ICD (P=0.70).

CONCLUSIONS

Primary prevention ICDs are associated with lower mortality in nonwhite and Hispanic patients, similar to that seen in white, non-Hispanic patients. These data support a similar approach to ICD patient selection, regardless of race or ethnicity.

Clinical effectiveness of CRT and ICD therapy in heart failure patients by racial/ethnic classification: insights from the IMPROVE HF registry

BACKGROUND

Clinical trials have demonstrated benefit for cardiac resynchronization therapy (CRT) and implantable cardioverter-defibrillator (ICD) therapies in patients with heart failure with reduced ejection fraction (HFrEF); yet, questions have been raised with regard to the benefit of device therapy for minorities.

OBJECTIVES

The purpose of this study was to determine the clinical effectiveness of CRT and ICD therapies as a function of race/ethnicity in outpatients with HFrEF (ejection fraction ≤35%).

METHODS

Data from IMPROVE HF (Registry to Improve the Use of Evidence-Based Heart Failure Therapies in the Outpatient Setting) were analyzed by device status and race/ethnicity among guideline-eligible patients for mortality at 24 months. Multivariate Generalized Estimating Equations analyses were conducted, adjusting for patient and practice characteristics.

RESULTS

The ICD/cardiac resynchronization defibrillator (CRT-D)-eligible cohort (n = 7,748) included 3,391 (44%) non-Hispanic white, 719 (9%) non-Hispanic black, and 3,638 (47%) other racial/ethnic minorities or race-not-documented patients. The cardiac resynchronization pacemaker (CRT-P)/CRT-D-eligible cohort (n = 1,188) included 596 (50%) non-Hispanic white, 99 (8%) non-Hispanic black, and 493 (41%) other/not-documented patients. There was clinical benefit associated with ICD/CRT-D therapy (adjusted odds ratio: 0.64, 95% confidence interval: 0.52 to 0.79, p = 0.0002 for 24-month mortality), which was of similar proportion in white, black, and other minority/not-documented patients (device-race/ethnicity interaction p = 0.7861). For CRT-P/CRT-D therapy, there were also associated mortality benefits (adjusted odds ratio: 0.55, 95% confidence interval: 0.33 to 0.91, p = 0.0222), and the device-race/ethnicity interaction was not significant (p = 0.5413).

CONCLUSIONS

The use of guideline-directed CRT and ICD therapy was associated with reduced 24-month mortality without significant interaction by racial/ethnic group. Device therapies should be offered to eligible heart failure patients, without modification based on race/ethnicity.

Outcomes in African Americans undergoing cardioverter-defibrillator implantation for primary prevention of sudden cardiac death: findings from the Prospective Observational Study of Implantable Cardioverter-Defibrillators (PROSE-ICD)

BACKGROUND

Implantable cardioverter-defibrillators (ICDs) reduce the risk of death in patients with left ventricular dysfunction. Little is known regarding the benefit of this therapy in African Americans (AAs).

OBJECTIVE

The purpose of this study was to determine the association between AA race and outcomes in a cohort of primary prevention ICD patients.

METHODS

We conducted a prospective cohort study of patients with systolic heart failure who underwent ICD implantation for primary prevention of sudden cardiac death. The primary end-point was appropriate ICD shock defined as a shock for rapid ventricular tachyarrhythmias. The secondary end-point was all-cause mortality.

RESULTS

There were 1189 patients (447 AAs and 712 non-AAs) enrolled. Over a median follow-up of 5.1 years, a total of 137 patients experienced an appropriate ICD shock, and 343 died (294 of whom died without receiving an appropriate ICD shock). The multivariate adjusted hazard ratio (95% confidence interval) comparing AAs vs non-AAs were 1.24 (0.96-1.59) for all-cause mortality, 1.33 (1.02, 1.74) for all-cause mortality without receiving appropriate ICD shock, and 0.78 (0.51, 1.19) for appropriate ICD shock. Ejection fraction, diabetes, and hypertension appeared to explain 24.1% (10.1%-69.5%), 18.7% (5.3%-58.0%), and 13.6% (3.8%-53.6%) of the excess risk of mortality in AAs, with a large proportion of the mortality difference remaining unexplained.

CONCLUSION

In patients with primary prevention ICDs, AAs had an increased risk of dying without receiving an appropriate ICD shock compared to non-AAs.

Barriers to patients eligible for screening investigations and insertion of primary prevention implantable cardioverter defibrillators

AIMS

Primary prevention (PP) implantable cardioverter defibrillator (ICD) implant rates in the UK are below national targets and barriers to this are not well known. This study was designed to identify the stages along the referral pathway from general to specialist care that eligible patients reach and what proportion eventually receive an ICD.

METHODS AND RESULTS

A single institution database search was performed to identify all adults with severe left ventricular systolic dysfunction (left ventricular ejection fraction, LVEF≤35%), documented in the calendar year 2007. Medical records were assessed for age, heart failure aetiology, QRS duration, evidence of non-sustained ventricular tachycardia on Holter, electrophysiological study, and records of consultation with general physicians, cardiologists, and electrophysiologists (EPs) and reference to assessment of risk of sudden cardiac death and the role of ICD implantation. Three hundred twenty-six patients with LVEF ≤ 35% were identified from three electronic databases. Mean age was 72 ± 12 years. Seventy-two patients satisfied UK National Institute for Clinical Excellence guidelines for PP ICD implantation and 63 eligible for further screening. Of the 135 patients, 76 (56%) patients reviewed by a general cardiologist did not receive ICD implantation or referral for further assessment. When offered, ICD acceptance rate was high (35 vs. 3 patients who refused ICD). After seeing an EP, 8 of 47 (17%) patients were not offered ICD or further screening. The average age was 66.5 ± 6.2 years and no patient greater than 80 years had a PP ICD.

CONCLUSIONS

Failure to refer from the general physician to cardiology and from the cardiologist to EP is the principle reason for low PP ICD implant rates among eligible patients in the UK.

Effectiveness of cardiac resynchronization therapy with defibrillator in at-risk black and white cardiac patients

BACKGROUND

There are limited data regarding racial differences in response to cardiac resynchronization therapy with defibrillator (CRT-D).

METHODS

We assessed the effectiveness of CRT-D, as compared to implantable cardioverter defibrillator (ICD) therapy alone, in reducing the risk of heart failure (HF) or death and changes in cardiac volumes among 1638 (90%) white patients and 143 (8%) black patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy (MADIT-CRT).

RESULTS

Enrolled black patients displayed a higher frequency of diabetes mellitus, treated hypertension, higher creatinine levels, and a lower distance walked in the baseline 6-minute walk test. Kaplan-Meier survival analysis showed that at 3 years of follow-up the cumulative probability of HF or death was higher among blacks (29%) as compared with whites (22%; P = 0.05). Both black and white patients experienced similar and pronounced reductions in cardiac volumes with CRT-D therapy (all P values for comparison between the two groups >0.10). Risk reduction conferred by CRT-D therapy as not significantly different between blacks and whites (hazard ratio = 0.78 and 0.60, respectively; P for the difference = 0.44). However, possibly due to sample size limitations the CRT-D versus ICD only adjusted risk for HF/death in blacks was not statistically significant.

CONCLUSIONS

Black patients in MADIT-CRT experienced increased risk of HF or death as compared with whites, but displayed a similar magnitude echocardiographic response to CRT-D. These findings suggest that cardiac resynchronization therapy may be an effective therapeutic modality in black patients. However, further studies are needed to assess the clinical response to CRT-D in this high-risk population.

Beat-to-beat three-dimensional ECG variability predicts ventricular arrhythmia in ICD recipients

BACKGROUND

Methodological difficulties associated with QT measurements prompt the search for new electrocardiographic markers of repolarization heterogeneity.

OBJECTIVE

We hypothesized that beat-to-beat 3-dimensional vectorcardiogram variability predicts ventricular arrhythmia (VA) in patients with structural heart disease, left ventricular systolic dysfunction, and implanted implantable cardioverter-defibrillators (ICDs).

METHODS

Baseline orthogonal electrocardiograms were recorded in 414 patients with structural heart disease (mean age 59.4 ± 12.0; 280 white [68%] and 134 black [32%]) at rest before implantation of ICD for primary prevention of sudden cardiac death. R and T peaks of 30 consecutive sinus beats were plotted in 3 dimensions to form an R peaks cloud and a T peaks cloud. The volume of the peaks cloud was calculated as the volume within the convex hull. Patients were followed up for at least 6 months; sustained VA with appropriate ICD therapies served as an end point.

RESULTS

During a mean follow-up time of 18.4 ± 12.5 months, 61 of the 414 patients (14.73% or 9.6% per person-year of follow-up) experienced sustained VA with appropriate ICD therapies: 41 of them were white and 20 were black. In the multivariate Cox model that included inducibility of VA and use of beta-blockers, the highest tertile of T/R peaks cloud volume ratio significantly predicted VA (hazard ratio 1.68, 95% confidence interval 1.01 to 2.80; P = .046) in all patients. T peaks cloud volume and T/R peaks cloud volume ratio were significantly smaller in black subjects (median 0.09 [interquartile range 0.04 to 0.15] vs. median 0.11 [interquartile range 0.06 to 0.22], P = .002).

CONCLUSION

A relatively large T peaks cloud volume is associated with increased risk of VA in patients with structural heart disease and systolic dysfunction.

Utility of the Seattle Heart Failure Model in patients with advanced heart failure

OBJECTIVES

The aim of this study was to validate the Seattle Heart Failure Model (SHFM) in patients with advanced heart failure (HF).

BACKGROUND

The SHFM was developed primarily from clinical trial databases and extrapolated the benefit of interventions from published data.

METHODS

We evaluated the discrimination and calibration of SHFM in 445 advanced HF patients (age 52 +/- 12 years, 68.5% male, 52.4% white, ejection fraction 18 +/- 8%) referred for cardiac transplantation. The primary end point was death (n = 92), urgent transplantation (n = 14), or left ventricular assist device (LVAD) implantation (n = 3); a secondary analysis was performed on mortality alone.

RESULTS

Patients were receiving optimal therapy (angiotensin-II modulation 92.8%, beta-blockers 91.5%, aldosterone antagonists 46.3%), and 71.0% had an implantable device (defibrillator 30.4%, biventricular pacemaker 3.4%, combined 37.3%). During a median follow-up of 21 months, 109 patients (24.5%) had an event. Although discrimination was adequate (c-statistic >0.7), the SHFM overall underestimated absolute risk (observed vs. predicted event rate: 11.0% vs. 9.2%, 21.0% vs. 16.6%, and 27.9% vs. 22.8% at 1, 2, and 3 years, respectively). Risk underprediction was more prominent in patients with an implantable device. The SHFM had different calibration properties in white versus black patients, leading to net underestimation of absolute risk in blacks. Race-specific recalibration improved the accuracy of predictions. When analysis was restricted to mortality, the SHFM exhibited better performance.

CONCLUSIONS

In patients with advanced HF, the SHFM offers adequate discrimination, but absolute risk is underestimated, especially in blacks and in patients with devices. This is more prominent when including transplantation and LVAD implantation as an end point.

Preventing tomorrow's sudden cardiac death today: dissemination of effective therapies for sudden cardiac death prevention

Because the burden of sudden cardiac death (SCD) is substantial, it is important to use all guideline-driven therapies to prevent SCD. Among those therapies is the implantable cardioverter defibrillator (ICD). When indicated, ICD use is beneficial and cost-effective. Unfortunately, studies suggest that most patients who have indications for this therapy for primary or secondary prevention of SCD are not receiving it. To explore potential reasons for this underuse and to propose potential facilitators for ICD dissemination, the Duke Center for the Prevention of SCD at the Duke Clinical Research Institute (Durham, NC) organized a think tank meeting of experts on this issue. The meeting took place on December 12 and 13, 2007, and it included representatives of clinical cardiology, cardiac electrophysiology, general internal medicine, economics, health policy, the US Food and Drug Administration, the Centers for Medicare and Medicaid Services, the Agency for Health care Research and Quality, and the device and pharmaceutical industry. Although the meeting was funded by industry participants, this article summarizing the presentations and discussions that occurred at the meeting presents the expert opinion of the authors.

Implantable device therapy

Sudden cardiac death (SCD) accounts for two-thirds of fatal events related to heart disease. Coronary heart disease and non-ischemic cardiomyopathy are the most common causes of SCD. Data from major randomized trials have consistently shown that therapy with an implantable cardioverter defibrillator (ICD) results in a significant and meaningful effect on survival through a reduction in the risk of SCD in these population. These data have resulted in a marked increase in the application of implantable device therapy in the past 2 decades from secondary prevention with an implantable cardioverter/defibrillator (ICD) in survivors of a cardiac arrest to primary prevention of SCD in asymptomatic patients with ischemic and non-ischemic left ventricular dysfunction, and prevention of symptomatic heart failure progression and death with cardiac resynchronization therapy (CRT), and devices that combine CRT and ICD therapies (CRT-D). However, there are still areas of uncertainty regarding device therapy that include inconsistent benefit in risk-subgroups of patients with low ejection fraction; increased risk of heart failure after life-prolonging ICD therapy, and a considerable rate of device malfunction despite increasing sophistication. In the present review we focus on current data regarding the clinical indications as well as the safety and efficacy of implantable device therapy, including ICD, CRT, and CRT-D.

Outcome in African Americans and other minorities in the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT)

BACKGROUND

The SCD-HeFT demonstrated that implantable cardioverter/defibrillator (ICD) therapy significantly improved survival compared to medical therapy alone in stable moderately symptomatic heart failure patients with an ejection fraction < or = 35%. The purpose of this report is to describe the outcomes in African Americans (AAs) and other minorities.

METHODS

Of 2521 patients enrolled, 23% were minorities and 17% were AAs. Baseline demographic, clinical variables, socioeconomic status, and long-term outcomes were compared according to race. Two major prespecified subgroups were examined: heart failure cause (ischemic vs nonischemic) and New York Heart Association class (II vs III).

RESULTS

At baseline, compared to whites, AAs were younger and had more nonischemic heart failure, lower ejection fractions, worse New York Heart Association functional class, and higher prevalence of a history of nonsustained ventricular tachycardia. Comparable percentages of whites and AAs held paid jobs, but whites had a significantly higher educational level and household income (P = .001). Compliance with ICD implantation and medical therapy was comparable in both subgroups. No significant difference was observed in the rate of ICD discharge among whites and AAs. Adjusted mortality risk was significantly higher in AAs compared to whites (hazard ratio 1.27, P = .038). Mortality was equally reduced in both race groups receiving ICD therapy compared to placebo (hazard ratio 0.65 in AAs and 0.73 in whites).

CONCLUSIONS

Survival benefits from ICD therapy in SCD-HeFT were not dependent on race. In addition, in this clinical trial setting, there was no evidence that AAs were less willing to accept ICD therapy than whites.

Prevalence and mortality of patients with myocardial infarction and reduced left ventricular ejection fraction in a defined community: Relation to the second multicenter automatic defibrillator implantation trial

OBJECTIVES

We compared characteristics and mortality of patients from a community population meeting enrollment criteria of the second Multicenter Automatic Defibrillator Implantation Trial (MADIT II) to those of the MADIT II subjects.

BACKGROUND

MADIT II showed that implantable cardioverter-defibrillators (ICDs) reduce mortality in patients with myocardial infarction (MI) and low left ventricular ejection fraction (LVEF) <or=30%.

METHODS

We used the resources of the Marshfield Epidemiologic Study Area (MESA), a well defined geographic region to identify MADIT II-type patients and determined outcomes during a 2-year follow-up period.

RESULTS

Of 1,126 patients who survived an MI, 114 (10.1%) had an LVEF <or=30%, 30 had exclusions leaving 84 patients meeting MADIT II-eligibility with a prevalence of 1.95/1,000. Applied to the US population, there would be about 360,000 MADIT II eligible individuals. MESA patients were older and more likely to be women than their MADIT II counterparts. The cumulative probability of death at 2 years in MESA patients (22.7%) was similar to the MADIT II control group (22%), whereas the sudden cardiac death (SCD) rate was lower in MESA (2.6%) than in MADIT II control patients (12%).

CONCLUSIONS

Differences in demographics, clinical characteristics and risk of SCD in community patients could alter the effectiveness and cost-effectiveness of ICD therapy from results reported in clinical trials. Further research is urgently needed to determine if the evidence-base used to formulate practice guidelines should be generalized to all individuals who meet eligibility criteria for ICD therapy.