Role of late potentials in identifying patients at risk for ventricular tachycardia after surgical correction of congenital heart disease.

This study evaluates the role of late potentials in identifying patients with sustained ventricular tachycardia (VT) after surgery for congenital heart defects using right ventriculotomy. Nine patients with early (1 to 12 months) or late VT (spontaneous in 7 [induced during electrophysiologic study in 6 of the 7] and induced in 2) and 104 patients without VT were studied. All patients had complete right bundle branch block. Late potentials were quantified by 3 time-domain parameters of the signal-averaged electrocardiogram: total filtered QRS duration, root-mean-square voltage in the last 40 ms, and low-amplitude signal duration of the terminal filtered QRS complex. Root-mean-square voltage filtered at 80 to 250 Hz was lower in patients with than without VT (9 +/- 6 vs 16 +/- 8 microV, p < 0.01). By multivariate analysis, more complex surgery (i.e., insertion of extracardiac conduits, Kawashima operation, etc.), lower root-mean-square voltage, and higher Lown grade (2 to 5) of ventricular arrhythmias on routine postoperative Holter recordings were the only independent predictors of VT (p < 0.001, < 0.05, and < 0.05, respectively). A combination of more complex surgery, root-mean-square voltage < 14 microV, and Lown grade 2 to 5 ventricular arrhythmias was highly predictive of VT (positive predictive value 75%). Conversely, patients without complex surgery and with root-mean-square voltage of > 13 microV were not likely to develop VT (negative predictive value 100%). Late potentials are an independent predictor of VT and may improve the identification of patients at low and high risk of VT after surgery for congenital heart defects using right ventriculotomy.