Conflicting data have emerged on the efficacy of implantable cardioverter defibrillators (ICDs) for primary prevention of sudden cardiac death (primary prevention ICDs) in patients with nonischemic cardiomyopathy.Objective
To investigate the association of primary prevention ICDs with all-cause mortality in patients with nonischemic cardiomyopathy.Data Sources
PubMed was searched from January 1, 2000, through October 31, 2016, for the terms implantable defibrillator OR implantable cardioverter defibrillator AND non-ischemic cardiomyopathy. Additional references were identified from bibliographies of pertinent articles and queries to experts in this field.Study Selection
Inclusion criteria consisted of a randomized clinical trial design and comparison of the ICD with medical therapy (control) in at least 100 patients with nonischemic cardiomyopathy. In addition, studies had to report on all-cause mortality during a follow-up period of at least 12 months and be published in English. The search yielded 10 studies, of which only 1 met the inclusion criteria. A search of bibliographies of pertinent articles and queries of experts in this field led to 3 additional studies.Data Extraction and Synthesis
The PRISMA guidelines were used to abstract data and assess data quality and validity. Data were pooled using fixed- and random-effects models.Main Outcomes and Measures
The primary end point was all-cause mortality. Before data collection started, primary prevention ICDs were hypothesized to reduce all-cause mortality among patients with nonischemic cardiomyopathy.Results
Four randomized clinical trials met the selection criteria and included 1874 unique patients; 937 were in the ICD group and 937 in the control group. Pooling data from these trials showed a significant reduction in all-cause mortality with an ICD (hazard ratio, 0.75; 95% CI, 0.61-0.93; P = .008; P = .87 for heterogeneity).Conclusions and Relevance
Primary prevention ICDs are efficacious at reducing all-cause mortality among patients with nonischemic cardiomyopathy. These findings support professional guidelines that recommend the use of ICDs in such patients.