Implantable cardioverter defibrillator (ICD) therapy reduces sudden cardiac death rates and reduces mortality in patients with ischemic heart disease and low ejection fractions. One-third of the deaths in patients with nonischemic cardiomyopathy are sudden. However, the efficacy of ICDs in the primary prevention of death in these patients is less clear. The most common cause of mortality in patients treated with ICDs is heart failure progression. ICD shocks can cause direct myocardial injury, fibrosis, inflammation, and adverse psychological outcomes, and these changes may contribute to the ventricular dysfunction in patients who already have a significantly depressed ejection fraction. We have reviewed the published randomized controlled trials and meta-analysis of prophylactic ICD therapy in the primary prevention of death in patients with nonischemic cardiomyopathy. The individual randomized controlled trials do not report a statistically significant reduction of mortality unless the ICD treatment is added to cardiac resynchronization therapy, but the meta-analysis did show a significant mortality reduction and favored ICD therapy in these patients. Medical management of many study participants was suboptimal, at least based on current guidelines. The patients with non-ischemic cardiomyopathy have good outcomes with medical therapy, and ICD therapy in this relatively low-risk population needs better selection criteria.
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