RIGHT VENTRICULAR OVERLOAD AND INDUCED SUSTAINED VENTRICULAR-TACHYCARDIA IN OPERATIVELY REPAIRED TETRALOGY OF FALLOT

The aim of the study was to evaluate the main predictors of the inducibility of sustained ventricular tachycardia (VT) in patients with repaired tetralogy of Fallot. Thirty-five patients (age 12 +/- 6 years) underwent right-sided cardiac catheterization, echocardiography, radionuclide angiography and ventricular stimulation; 10 had (group 1) and 25 had no (group 2) sustained VT. Group 1 patients were significantly older at the time of surgery and had longer follow-up periods (7 +/- 3 vs 4 +/- 4 years, p < 0.02; and 12 +/- 4 vs 5 +/- 2 years, p < 0.001, respectively). Right ventricular (RV) systolic pressure, end-systolic and end-diastolic normalized RV volumes were higher in group 1 (48 +/- 14 vs 38 +/- 11 mm Hg, p < 0.05; 1.23 +/- 0.2 vs 0.86 +/- 0.17, p < 0.001; and 2.35 +/- 0.37 vs 1.70 +/- 0.22, p < 0.001, respectively). RV end-diastolic pressure, left ventricular and RV ejection fractions were similar in the 2 groups. A stepwise discriminant analysis was made to predict patients with inducible sustained VT (group 1): Time period from surgery to follow-up (p < 0.001), normalized RV end-systolic volume (p < 0.002) and RV systolic pressure (p = 0.01) were higher in group 1 and allowed classification of 90% of patients in group 1 and 96% in group 2. Although a longer time from surgery was a major predictor of inducible sustained VT, the presence of either RV systolic barometric or volumetric overload was also an important independent predictor, which suggests that increased RV systolic wall stress may be an essential determinant of sustained VT inducibility.