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)

Arrhythmia and Survival Outcomes Among Black Patients and White Patients With a Primary Prevention Defibrillator

BACKGROUND

Black Americans have a higher risk of nonischemic cardiomyopathy (NICM) than White Americans. We aimed to evaluate differences in the risk of tachyarrhythmias among patients with an implantable cardioverter-defibrillator (ICD).

METHODS

The study population comprised 3895 ICD recipients in the United States enrolled in primary prevention ICD trials. Outcome measures included ventricular tachyarrhythmia (VTA), atrial tachyarrhythmia (ATA), ICD therapies, VTA burden (using Andersen-Gill recurrent event analysis), death, and the predicted benefit of the ICD. All events were adjudicated blindly. Outcomes were compared between self-reported Black patients versus White patients with cardiomyopathy (ischemic and NICM).

RESULTS

Black patients were more likely to be female (35% versus 22%) and younger (57±12 versus 62±12 years) with a higher frequency of comorbidities. In NICM, Black patients had a higher rate of first VTA, fast VTA, ATA, and appropriate and inappropriate ICD therapy (VTA ≥170 bpm, 32% versus 20%; VTA ≥200 bpm, 22% versus 14%; ATA, 25% versus 12%; appropriate therapy, 30% versus 20%; and inappropriate therapy, 25% versus 11%; P<0.001 for all). Multivariable analysis showed that Black patients with NICM experienced a higher risk of all types of arrhythmia or ICD therapy (VTA ≥170 bpm, hazard ratio [HR] 1.71; VTA ≥200 bpm, HR 1.58; ATA, HR 1.87; appropriate therapy, HR 1.62; inappropriate therapy, HR 1.86; P≤0.01 for all), higher burden of tachyarrhythmias or therapies (VTA, HR 1.84; appropriate therapy, HR 1.84; P<0.001 for both), and a higher risk of death (HR 1.92; P=0.014). In contrast, in ischemic cardiomyopathy, the risk of all types of tachyarrhythmia, ICD therapy, or death was similar between Black patients and White patients. Both Black patients and White patients derived a significant and similar benefit from ICD implantation.

CONCLUSIONS

Among patients with NICM with an ICD for primary prevention, Black patients compared with White patients had a high risk and burden of VTA, ATA, and ICD therapies with a lower survival rate. Nevertheless, the overall benefit of the ICD was maintained and was similar to that of White patients.

Arrhythmia and Survival Outcomes among Black and White Patients with a Primary Prevention Defibrillator

Background

Black Americans have a higher risk of non-ischemic cardiomyopathy (NICM) than White Americans. We aimed to evaluate racial disparities in the risk of tachyarrhythmias among patients with an implantable cardioverter defibrillator (ICD).

Methods

The study population comprised 3,895 ICD recipients enrolled in the U.S. in primary prevention ICD trials. Outcome measures included first and recurrent ventricular tachy-arrhythmia (VTA) and atrial tachyarrhythmia (ATA), derived from adjudicated device data, and death. Outcomes were compared between self-reported Black vs. White patients with a cardiomyopathy (ischemic [ICM] and NICM).

Results

Black patients were more likely to be female (35% vs 22%) and younger (57±12 vs 62±12) with a higher frequency of comorbidities. Blacks patients with NICM compared with Whites patients had a higher rate of first VTA, fast VTA, ATA, appropriate-, and inappropriate-ICD-therapy (VTA≥170bpm: 32% vs. 20%; VTA≥200bpm: 22% vs. 14%; ATA: 25% vs. 12%; appropriate 30% vs 20%; and inappropriate: 25% vs. 11%; p<0.001 for all). Multivariable analysis showed that Black patients with NICM experienced a higher risk of all types of arrhythmia/ICD-therapy (VTA≥170bpm: HR=1.69; VTA≥200bpm: HR=1.58; ATA: HR=1.87; appropriate: HR=1.62; and inappropriate: HR=1.86; p≤0.01 for all), higher burden of VTA, ATA, ICD therapies, and a higher risk of death (HR=1.86; p=0.014). In contrast, in ICM, the risk of all types of tachyarrhythmia, ICD therapy, or death was similar between Black and White patients.

Conclusions

Among NICM patients with an ICD for primary prevention, Black compared with White patients had a high risk and burden of VTA, ATA, and ICD therapies.

Clinical Perspective

What Is New?: Black patients have a higher risk of developing non-ischemic cardiomyopathy (NICM) but are under-represented in clinical trials of implantable cardioverter defibrillators (ICD). Therefore, data on disparities in the presentation and outcomes in this population are limited.This analysis represents the largest group of self-identified Black patients implanted in the U.S. with an ICD for primary prevention with adjudication of all arrhythmic events.What Are the Clinical Implications?: In patients with a NICM, self-identified Black compared to White patients experienced an increased incidence and burden of ventricular tachyarrhythmia, atrial tachyarrhythmia, and ICD therapies. These differenced were not observed in Black vs White patients with ischemic cardiomyopathy (ICM).Although Black patients with NICM were implanted at a significantly younger age (57±12 vs 62±12 years), they experienced a 2-fold higher rate of all-cause mortality during a mean follow up of 3 years compared with White patients.These findings highlight the need for early intervention with an ICD, careful monitoring, and intensification of heart failure and antiarrhythmic therapies among Black patients with NICM.

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.

Heart Failure with Improved Ejection Fraction: Insight into the Variable Nature of Left Ventricular Systolic Function

The progress of contemporary cardiovascular therapy has led to improved survival in patients with myocardial disease. However, the development of heart failure (HF) represents a common clinical challenge, regardless of the underlying myocardial pathology, due to the severely impaired quality of life and increased mortality comparable with malignant neoplasms. Left ventricular ejection fraction (LVEF) is the main index of systolic function and a key predictor of mortality among HF patients, hence its improvement represents the main indicator of response to instituted therapy. The introduction of complex pharmacotherapy for HF, increased availability of cardiac-implantable electronic devices and advances in the management of secondary causes of HF, including arrhythmia-induced cardiomyopathy, have led to significant increase in the proportion of patients with prominent improvement or even normalization of LVEF, paving the way for the identification of a new subgroup of HF with an improved ejection fraction (HFimpEF). Accumulating data has indicated that these patients share far better long-term prognoses than patients with stable or worsening LVEF. Due to diverse HF aetiology, the prevalence of HFimpEF ranges from roughly 10 to 40%, while the search for reliable predictors and genetic associations corresponding with this clinical presentation is under way. As contemporary guidelines focus mainly on the management of HF patients with clearly defined LVEF, the present review aimed to characterize the definition, epidemiology, predictors, clinical significance and principles of therapy of patients with HFimpEF.

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.