Electrocardiographic risk stratification in dilative cardiomyopathy: an unfulfilled promise.

Idiopathic dilated cardiomyopathy represents the substrate for approximately 10% of sudden cardiac deaths in the adult population. Mortality in patients with dilated cardiomyopathy ranges between 10% and 50% annually, mainly determined by the severity of the disease. Tamburro and Wilber compiled 14 studies including a total of 1432 patients and demonstrated an average mortality rate over 4 years of 42%; 28% of all fatalities were classified as sudden deaths. According to other investigators, sudden death may indeed be responsible for up to 50% of fatalities particularly in patients with NYHA class II or III heart failure. Recently, it has been demonstrated that in patients with a history of sustained ventricular tachycardia or aborted sudden death, the implantable defibrillator is superior to antiarrhythmic pharmacotherapy in prolonging life. In these studies, a significant proportion of enrolled patients suffered from dilated cardiomyopathy as the underlying heart disease. Even in dilated cardiomyopathy patients without aborted sudden death but with syncope as the initial presentation in whom no arrhythmias could be provoked at electrophysiological testing, there was a high incidence of appropriate device therapy during a follow-up of 24 13 months. It appears conceivable, therefore, that device therapy may similarly be capable of reducing sudden death in patients with dilated cardiomyopathy without prior ventricular tachyarrhythmic episodes or syncope. However, accurate identification of patients with dilated cardiomyopathy being at high risk of arrhythmogenic death is mandatory since prophylactic ICD implantation in all patients presenting with this type of structural heart disease will not be feasible. Moreover, widespread application of such an approach requires non-invasive, inexpensive, and easy to perform risk stratification methods. Accordingly, in recent years numerous studies have been published examining this important issue. In general, the results of many of these studies have