Update on Ventricular Tachyarrhythmias and Related Sudden Cardiac Death

Goldberger JJ and colleagues have provided a meta analysis on risk stratification for arrhythmic events in nonischemic dilated cardiomyopathy [1]. They identified 45 studies with over six thousand participants which looked at arrhythmic events and predictive tests [Table 1]. They found that the tests of autonomic variability like heart rate variability, heart rate turbulence and baroreflex sensitivity were unable to predict arrhythmic outcomes to a significant extent. Other tests which include functional parameters, arrhythmic markers and depolarization / repolarization abnormalities have only a modest value in prediction of risk of sudden cardiac death in nonischemic dilated cardiomyopathy. Authors suggested that a combination of tests will be needed for optimal risk prediction in nonischemic dilated cardiomyopathy. This may be because multiple factors are involved in the pathogenesis of arrhythmia in nonischemic dilated cardiomyopathy, unlike in ischemic cardiomyopathy. Risk stratification is of paramount importance on deciding who should receive the limited and costly resource of an implantable cardioverter defibrillator. Ideally a good risk stratification method should give an odds ratio of more than 15, while most of the present risk stratification methods give an odds ration in the range of 2. It is also worth noting that most sudden cardiac deaths occur in those who cannot be identified by current risk stratification methods.