Relation between microvolt level T wave alternans and other potential noninvasive predictors of arrhythmic risk in the marburg cardiomyopathy study

The relation between microvolt level T wave alternans (TWA) and other nonin vasive arrhythmia risk predictors was analyzed in 221 consecutive patients with idiopathic dilated cardiomyopathy (IDC) and sinus rhythm enrolled in t he Marburg Cardiomyopathy Study between March 1996 and May 2000. TWA analys is wets also performed in 110 healthy controls of similar age and sex. TWA during symptom-limited exercise was positive, negative and indeterminate in , respectively, 108 (49%), 65 (29%) and 48 (22%) patients with IDC versus, respectively, 5 (5%), 98 (89%) and 7 (6%) healthy controls (P < 0.05). Pati ents with IDC and positive TWA had a lower left ventricular (LV) ejection f raction (29 +/- 9% vs 34 +/- 10%, P < 0.05) and greater LV end-diastolic di ameter (69 +/- 8 mm versus 64 +/- 6 mm, P < 0.05) than patients with negati ve TWA. Other variables, including age, gender, New York Heart Association functional class, presence of bundle branch block, arrhythmias on 24-hour a mbulatory electrocardiogram, heart rate variability and baroreflex sensitiv ity, were not significantly different between patients with positive vs neg ative TWA. The prognostic significance of TWA in IDC with regard to arrhyth mic events and total mortality will be determined by multivariate Cox analy sis at the end of a 5-year follow-up in this ongoing study.