Mortality Effect of ICD in Primary Prevention of Nonischemic Cardiomyopathy: A Meta‐Analysis of Randomized Controlled Trials

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Implantation of an implantable cardioverter defibrillator (ICD) for primary prevention of sudden cardiac death (SCD) is a class 1 indication in the current clinical practice1 guidelines for patients with heart failure and a low ejection fraction. Although commonly used in clinical practice, acquisition of ICDs in the United States range from approximately $18,000 for the simplest devices to over $35,000 for ICDs with biventricular pacing capabilities.3 This has led to significant strain on the budgets of many healthcare systems leading to the importance of identifying and preventing implanting ICD in populations who would not benefit.
There is strong evidence supporting the mortality benefit of ICD in primary prevention of SCD in ischemic cardiomyopathy.4 However, the evidence supporting the use of ICD in primary prevention of SCD with nonischemic cardiomyopathy (NICMP) is not very robust. The current guidelines are based on a meta‐analysis5 of five RCTs which were limited by their conflicting results with the positive results driven mainly by the Sudden Cardiac Death in Heart Failure Trial (SCD‐HeFT)6 and Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION) trial.7 The negative trials exclusively enrolled patients with NICMP, while the positive trials (SCD‐HeFT trial and COMPANION) also included patients with ischemic cardiomyopathy and studied the effect of NICMP in its subanalysis. The COMPANION trial did not study the role of ICD independently as these patients also had cardiac resynchronization therapy (CRT), which had independent mortality benefits. Recently the Danish Study to Assess the Efficacy of ICDs in Patients with Non‐Ischemic Systolic Heart Failure on Mortality (DANISH) reported the lack of any survival benefit of ICD in patients with NICMP. However, 58% of the patients in the DANISH study had CRT implantation and thus the study did not address the mortality effects in NICMP patients who only had ICDs. In light of the recent results from the DANISH trial along with the importance of ICDs from a clinical and a public health perspective, we conducted a meta‐analysis of the randomized controlled trials to evaluate the efficacy of primary prevention ICDs in NICMP. The meta‐analysis aims to help us to better understand the differences in the results of these trials and the applicability of these different trials to the current patient population in view of the changes in guideline directed medical therapy over the years.
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