Non-invasive detection of late potentials in man–a new marker for ventricular tachycardia*

Late potentials occurring after the QRS complex were searched for from the body surface using high-gain amplification and signal averaging techniques with filler sellings between 100 and 300 Hz at a sampling rate of 10 kHz. The number of repetitions of the averaging process ranged between 150 and 300 Hz. Sixty-seven patients were studied. In 11 control subjects, no late potentials were delected within the ST segment. Late potentials were observed in 3/27 patients without previously documented ventricular tachycardia all having left ventricular aneurysms. All three patients had evidence of increased ventri-l cular vulnerability (one dying from ventricular tachycardia; one with stimulus-inducible ventricular tachy–cardia; one with multiple episodes of ventricular fibrillation after surgery). In patients with previously k documented ventricular tachycardia and/or fibrillation, late potentials occurred in 7/14 cases (50%), mainly in those with aneurysms (6/8 patients = 7596/ In another 15 patients with ventricular tachycardia and/or fibrillation who were on an effective long-term antiarrhylhmic regimen no late potentials were found. Mean onset of late potentials after the QRS complex was 38 ± 20.1 ms, mean amplitude was 3.9 ± 2.0 uv, and mean duration was 17.1 ± 5.4 ms. We conclude that late potentials which represent late depolarization of a mass of ventricular tissue after slow conduction, herald increased susceptibility to ventricular tachyardia mainly in patients with ventricular aneurysms.