Prediction of Sudden Cardiac Death in Patients With Coronary Heart Disease

Abstract

Despite widespread advances in coronary heart disease (CHD) treatment and the growing use of implantable cardioverter-defibrillators (ICDs), sudden cardiac death (SCD) remains a major cause of CHD death in the United States,1 and identification of patients at risk for SCD remains a challenge. Left ventricular ejection fraction (LVEF) has been found to be the strongest independent predictor of SCD among traditional clinical markers,2 and risk of SCD exponentially increases as LVEF decreases.3 Based on data from observational studies, clinical trials were designed to test the hypothesis that ICD therapy would prolong life in patients with clinically recognized left ventricular dysfunction. Although these trials have demonstrated convincing survival benefits,4,5 there continues to be great debate regarding the overall effectiveness, and in particular cost-effectiveness, of the current strategy of allocating ICD therapy on the basis of LVEF.6,7 Article see p 180 Stratifying SCD risk based solely on LVEF has 2 important well-recognized limitations. First, LVEF lacks specificity in that it not only predicts SCD but other modes of cardiovascular death as well.8 Indeed, most current clinical predictors, with the possible exception of invasive electrophysiological testing,9 predict cardiovascular death in general rather than mode of death. Thus, these predictors in isolation are unable to discriminate those who will die suddenly from those who will die from other causes. Although defibrillators are highly effective at terminating potentially lethal ventricular arrhythmias, recent estimates suggest that allocating ICD therapy on the basis of LVEF may not be cost-effective until 8 years after implantation,10 a timeline that exceeds the length of follow-up in completed randomized trials.4,5 If patients deemed “high-risk” for SCD are at an equally high risk of dying from other causes, the benefit of the ICD may not be realized. Second, the measurement of LVEF lacks …