Prevalence of late potentials in patients with and without ventricular tachycardia: correlation with angiographic findings.

Late potentials occurring at the end of or after the QRS complex were searched for from the body surface using high gain amplification and signal averaging techniques with filter settings between 100 and 300 hertz. The number of repetitions of the averaging process ranged between 150 and 300. Two hundred thirty-six patients were studied. In 27 control subjects, no late potentials were recorded. Among 146 patients without ventricular tachycardia or fibrillation, late potentials were present in 49 (34 percent). The mean duration of late potentials was 31 +/- 15.3 ms (median 25). Of 63 patients with documented ventricular tachycardia or fibrillation, 45 (71 percent) had late potentials (mean duration 51 +/- 31.5 ms; median 50) (probability [p] greater than 0.001). There was a close correlation between the detection of late potentials and left ventricular function. Late potentials occurred more frequently in patients with than in those without ventricular akinesia or aneurysm and in patients with than in those without ventricular tachycardia or fibrillation. In conclusion, late potentials are a frequent finding in patients with regional contraction abnormalities, both in patients with and in those without documented ventricular tachycardia. The greater prevalence and longer duration of these signals in patients with ventricular tachycardia or fibrillation might be responsible for the greater susceptibility to ventricular tachycardia. Long-term follow-up studies will be necessary to assess the possible prognostic significance of late potentials in patients without previously documented ventricular tachycardia or fibrillation.