Sudden cardiac death in nonischemic cardiomyopathy

Sudden cardiac death (SCD) is a major cause of mortality in patients with nonischemic cardiomyopathy (NICM). Identifying patients who are at highest risk for SCD is an ongoing challenge. At present, guidelines recommend the use of an implantable cardioverter-defibrillator (ICD) in patients with NICM with a reduced left ventricular ejection fraction (LVEF) and heart failure (HF) symptoms. Some recent data, however, suggest that ICDs may not increase longevity in this population. Conversely, community-based studies have demonstrated that many at-risk individuals who may benefit from ICD therapy remain unprotected. Current recommendations for ICD implantation are continually debated, justifying comprehensive individualized risk assessment. Various promising techniques for further risk stratification are under evaluation, including cardiac magnetic resonance imaging, electrocardiographic assessment of electrical instability, and genetic testing. However, none of these strategies has been fully adapted into guidelines. Hence, clinical risk stratification practice today depends on LVEF and HF symptoms, which have poor sensitivity and specificity for predicting SCD risk.