Significance of ventricular late potentials in non-ischaemic dilated cardiomyopathy.

To assess the incidence and clinical significance of ventricular late potentials in non-ischaemic dilated cardiomyopathy, 51 consecutive (44 male, seven female, mean age 53 +/- 11 years) patients with dilated cardiomyopathy were studied. Twenty-eight patients (55%) were in New York Heart Association functional class III or IV, 34 out of 51 (76%) had a left ventricular ejection fraction of less than 40%, 10 out of 51 (20%) had a history of sustained ventricular tachycardia (VT), 24 out of 37 (65%) had runs of non-sustained ventricular tachycardia during Holter monitoring and 15 out of 51 (29%) had a left bundle branch block. A signal-averaged electrocardiogram (gain 10(6) x, bipolar chest leads, filters 100-300 Hz) was performed in all the patients; late potentials were considered present if the total filtered QRS duration was longer than 118 ms and the interval between the end of QRS and the voltage 40 microV was more than 40 ms in the absence of left bundle branch block (total filtered QRS duration greater than 140 ms and interval between the end of QRS and the voltage 40 microV greater than 50 ms in the presence of left bundle branch block). Ventricular late potentials were detected in 22 out of 51 patients (43%). Late potentials were present in 80% (eight out of 10) of patients with sustained ventricular tachycardia but in only 34% (14 of 41) without sustained ventricular tachycardia (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)