Predicting the Future

Abstract

It's tough to make predictions, especially about the future. —Yogi Berra Risk stratification for any disease is, in many ways, medicine's attempt to predict the future. The challenges in risk stratification for sudden death, however, may be unparalleled in medicine. Although the many types of sudden death all present with similar phenotypes, risk stratification efforts generally center on the prediction of death resulting from either ischemic or arrhythmic events. The focus of this article is on current and future approaches to risk stratification for sudden death caused by ventricular tachyarrhythmias in patients with left ventricular dysfunction (referred to here as sudden cardiac death [SCD]). Recent advances that limit the myocardial injury and remodeling that leads to left ventricular dysfunction continue to favorably affect SCD rates. However, the prevalence of SCD and the low survival rate once it occurs remain major public health concerns and underscore the importance of risk stratification and preemptive intervention. For many other disease processes for which risk factors are established or sought, investigators have successfully relied on objective criteria to define the end point of interest such as myocardial infarction (MI). For SCD, we have often depended on clinical trials that assessed arrhythmic death or surrogate markers such as appropriate implantable cardioverter-defibrillator (ICD) therapy or total mortality. Many of these end points, however, may not accurately assess the occurrence of fatal ventricular tachyarrhythmias that are otherwise amenable to defibrillation. Our ability to correctly distinguish cause of death on clinical grounds is marginal at best, with data suggesting that at least in patients with ischemic heart disease, we may be wrong nearly half the time. For example, in a substudy of the Valsartan in Acute Myocardial Infarction (VALIANT) trial, autopsies were performed on post-MI patients whose deaths were considered sudden on clinical grounds. Of these, 49% were …