Effects of Nonsystemic Ventricular Pacing in Patients with Transposition of the Great Arteries and Atrial Redirection

Abstract

Ventricular pacing may add additional risk for right ventricular (RV) dysfunction in patients with transposition of the great arteries (TGA) and atrial redirection. The aim of our study was to evaluate the effects of long-term nonsystemic ventricular pacing on cardiac function, dyssynchrony, and clinical performance in patients with systemic RV. Forty-six adults with TGA and atrial redirection, of whom 11 were permanently paced at the nonsystemic ventricle, underwent assessment of clinical status and exercise stress testing, as well as echocardiography to assess parameters of RV function and dyssynchrony. In paced patients, median NYHA functional class was II, which was significantly higher than in nonpaced patients (median class I; P = 0.002). Maximum performance and peak oxygen consumption on exercise testing were significantly lower in paced patients when compared with nonpaced patients (100 ± 30 vs 120 ± 32 W and 22 ± 6 vs 27 ± 7 mLO(2)/kg/min, respectively; P < 0.05 for both). On echocardiography, RV shortening fraction (27 ± 11 vs 33 ± 10%), RV ejection fraction (39 ± 7 vs 44 ± 10%) and RV dP/dt(max) (891 ± 470 vs 1,024 ± 318 mmHg/s) were significantly lower (P < 0.05 for all) in paced versus nonpaced patients. Inter- and intraventricular dyssynchrony was most pronounced in the paced group (99 ± 10 vs 25 ± 9 ms and 70 ± 29 vs 21 ± 15 ms, respectively; P < 0.001 for both). Long-term pacing of the nonsystemic ventricle in patients with atrial switch for TGA was associated with significantly impaired functional status, exercise capacity, and systemic ventricular function.