Arrhythmia risk stratification in idiopathic dilated cardiomyopathy based on echocardiography and 12-lead, signal-averaged, and 24-hour Holter electrocardiography

Background To date, considerable controversy exists regarding noninvasive a rrhythmia risk stratification in idiopathic dilated cardiomyopathy (IDC). Methods and Results Between 1992 and 1997, 202 patients with IDC without a history of sustained ventricular tachycardia (VT) underwent echocardiograph y, signal-averaged electrocardiogram (ECG), and 24-hour Holter ECG in the a bsence of antiarrhythmic drugs. During 32 +/- 15 months of prospective foll ow-up, major arrhythmic events, including sustained VT, ventricular fibrill ation, or sudden death, occurred in 32 (16%) of 202 patients. After adjusti ng for baseline medical therapy and antiarrhythmic therapy during follow-up , multivariate Cox regression analysis identified a left ventricular (LV) e nd-diastolic diameter greater than or equal to 70 mm and nonsustained VT on Hotter as the only independent arrhythmia risk predictors. The combination of an LV end-diastolic diameter greater than or equal to 70 mm and nonsust ained VT was associated with a 14.3-fold risk for future arrhythmic events (95% confidence interval 2.3-90). To further elucidate the prognostic value of LV election fraction, multivariate Cox analysis was repeated with elect ion fraction forced to remain in the model. In the latter model, an electio n fraction less than or equal to 30% combined with nonsustained Vi on Holte r was found to be a significant arrhythmia risk predictor with a relative r isk of 14.6 (95% confidence interval 2.2-97). Conclusions The combination of an LV end-diastolic diameter greater than or equal to 70 mm and nonsustained VT on Hotter, and the combination of LV el ection fraction less than or equal to 30% and nonsustained VT on Holter, id entify a subgroup of patients with IDC with a 14-fold risk for subsequent a rrhythmic events. These findings have important implications for the design of future studies evaluating the role of prophylactic defibrillator therap y in patients with IDC.