Body surface late potentials: effects of endocardial resection in patients with ventricular tachycardia.

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Abstract
We studied 37 patients undergoing endocardial resection for medically refractory ventricular tachycardia (VT). Each was studied before and after surgery by programmed ventricular stimulation and signal-averaged electrocardiography. Low-amplitude late potentials were identified preoperatively in 76% of patients. In the 24 patients without postoperative VT the effect of surgery was to shorten the filtered QRS duration (137 +/- 27 to 121 +/- 26 msec; p = .003), increase the voltage in the last 40 msec of the filtered QRS (16.5 +/- 16.1 to 39.0 +/- 29.4 microV; p = .003), and decrease the incidence of late potentials (71% to 33%; p = .03). The filtered QRS complex was unchanged in 13 patients whose VT persisted after surgery. No preoperative variable predicted which patients would not have inducible VT after surgery. However, loss of a late potential after surgery in nine of 10 patients was associated with absence of inducible VT (p less than .02). Loss of a late potential was not necessary for surgical success. Eight of 18 patients with a persistent late potential did not have inducible VT. The signal-averaged electrocardiogram predicted a successful outcome after endocardial resection if the late potential was no longer present.