Effects of cardiac resynchronization therapy on echocardiographic indices, functional capacity, and clinical outcomes of patients with a systemic right ventricle.

AIMS Surgically (SC) or congenitally corrected (CC) transposition of the great arteries (TGA), associated with a systemic right ventricle (RV), is often complicated by heart failure. This retrospective study assessed the functional and mechanical effects of cardiac resynchronization therapy (CRT) in patients presenting with TGA. METHODS AND RESULTS Seven patients with SC (n = 5) or CC (n = 2) TGA (mean age 24.6 +/- 12 years), a failing systemic RV, and intraventricular dyssynchrony, underwent implantation of a CRT-P. Permanent pacemakers were previously implanted in five patients. The leads were implanted by a combined transvenous and epicardial approach in the five patients with SC TGA. Echocardiography, including tissue Doppler imaging and cardiopulmonary exercise testing were performed before and during CRT. Since, in all patients, ventricular dyssynchrony was due to delayed septal wall contraction, the interventricular septum and RV free wall were stimulated synchronously, with a view to resynchronize a maximum amount of myocardium. After 19.4 +/- 8.1 months of CRT, mean QRS duration decreased from 160 +/- 31 to 120 +/- 28 ms (P = 0.03), intraventricular delay from 104 +/- 27 to 14 +/- 15 ms (P = 0.01), New York Heart Association functional class from 3.0 to 1.57 (P = 0.01), and peak oxygen consumption increased from 13.8 +/- 2.5 to 22.8 +/- 6.7 mL/kg/min (P = 0.03). One patient died suddenly at 23 months of follow-up. CONCLUSIONS CRT was technically feasible and associated with improvements in cardiac mechanical function and clinical status in patients with TGA, failing systemic RV, and intraventricular dyssynchrony.