[Response of ventricular late potentials after surgical therapy of ventricular tachycardia]

19 patients with either previously documented sustained ventricular tachycardia (VT) (n = 16) or only inducible VT (n = 3, one of whom had recurrent syncope), due to previous myocardial infarction were studied pre- and postoperatively. Mean age was 53 +/- 6 years, 16 were male, 3 female. In all but one, VT could be induced preoperatively by programmed right ventricular stimulation. Late potentials (LP) were recorded at the end of or after the QRS-complex from the body surface using high-gain amplification and the signal averaging technique (RC-filter settings 100 to 300 Hz). Indication for surgery was either intractable VT or bypass grafting and/or aneurysmectomy. Preoperatively, mean duration of late potentials was 54 +/- 37.7 ms, mean amplitude was 12 +/- 14.0 mean V. Surgery was guided by epi- and endocardial mapping. In 14 cases endomyocardial encircling ventriculotomy was the main procedure, whereas in 5 patients only aneurysmectomy and bypass grafting were performed. Postoperatively, late potentials were no longer detectable in 12 cases, whereas in 6 of 7 cases there was a decrease in duration, but no essential change in amplitude. A postoperative electrophysiological study was performed in 18 cases. In those 12 patients with abolition of LPs, the maximal number of inducible ventricular echo beats using an extended stimulation program from three right ventricular sites, ranged between 1 and 5 in 9 cases, between 10 and 11 VE in 2 cases, whereas VT was induced in only 1 case. In 6 patients in whom LPs were still detectable, ventricular tachycardia could still be induced in 2 cases and a maximal response of ten echo beats was observed in another patient. Abolition of LP by surgery is closely related to the disappearance of the propensity to stimulus-induced VT. Thus the averaging technique may provide a non-invasive procedure to assess the successful outcome after operation for ventricular tachycardia. If, however, LPs are still present, this does not exclude successful surgical abolition of the propensity to ventricular tachycardia.