Prognostic value of late potentials in patients with congestive heart failure.

To investigate whether detection of ventricular late potentials could provide prognostic information in patients with congestive heart failure with or without bundle branch block, we prospectively obtained a signal-averaged ECG from 151 patients with congestive heart failure, using specific criteria in 57 patients with bundle branch block. Late potentials were detected in 49 patients (32.5%); their incidence was not significantly different in patients without (31%; 29 patients) or with bundle branch block (35%; 20 patients). Late potentials were present in 25 of 73 patients (34%) with idiopathic dilated cardiomyopathy, in 20 of 57 patients (35%) with ischaemic cardiomyopathy and in four of 21 patients (19%) with hypertensive heart disease (ns). Age, NYHA class, ejection fraction and use of amiodarone were not statistically different among patients with or without late potentials. In contrast, patients with late potentials had more past episodes of sustained ventricular tachycardia (8.2%; four patients) than those without late potentials (1.9%; two patients). Twenty four hour ambulatory ECGs were obtained in 135 patients (89%). Non-sustained ventricular tachycardia was not correlated with the presence of late potentials found in 45 of 88 patients (51%) without late potentials and in 29 of 47 patients (62%) with late potentials (ns). The mean follow-up was 27 +/- 12 months; 51 patients died, 31 from progressive congestive heart failure and 13 suddenly; seven prospectively had sustained ventricular tachycardia. The total mortality rate, the cardiac mortality rate and sudden death risk were not significantly related to the presence of late potentials; their incidence were respectively 35% (36 patients), 32% (33 patients) and 10% (10 patients) in patients without late potentials and 31% (15 patients), 23% (11 patients) and 6% (three patients) in those without late potentials. The incidence of sustained ventricular tachycardia during follow-up was 2% (two patients) in patients without late potentials and 10% (five patients) in those with late potentials. The incidence of sustained ventricular tachycardia experienced by the patients before the study or seen during follow-up was significantly increased in the presence of late potentials: 18% (nine patients) vs 2% (two patients) in the absence of late potentials (P < 0.001). Removal from the study of data from patients with bundle branch block, patients with severe congestive heart failure (NYHA 3 or 4) or patients taking amiodarone did not alter these results. Thus, signal-averaged ECG results only improved risk stratification for sustained ventricular tachycardia in patients with congestive heart failure and failed to identify patients at high risk for sudden death.