Prediction of sudden cardiac death: next steps in pursuit of effective methodology

Abstract

The recognition that severe left ventricular dysfunction is a predictor of sudden cardiac death (SCD) risk enabled widespread utilization of the implantable cardioverter defibrillator (ICD) for SCD prevention. Use of the ICD prior to any signs or symptoms of ventricular arrhythmias (“primary prevention”) is particularly important for SCD because case fatality for patients with sustained ventricular tachyarrhythmias is among the highest of any disease process. At the same time, primary prevention of SCD presents a unique epidemiologic challenge for many reasons [1, 2]: (1) high-risk subgroups constitute only a small proportion of all patients at risk for SCD, (2) the pathophysiologic etiologies of SCD are complex and infrequently recognized prior to arrest, (3) ventricular arrhythmia substrate often evolves over time and may require repeated risk stratification, (4) classification of arrhythmic death is particularly imprecise, (5) triggers for SCD may be transient, and (6) patients at high risk for SCD have many competing risks that are not ameliorated by ICDs. This review will address the limitations of risk stratification based on left ventricular ejection fraction (LVEF), summarize new developments in the field that extend beyond LVEF, and suggest new investigative approaches for refinement of SCD risk assessment.