Cardiac resynchronization therapy among adults with a systemic right ventricle: a multicenter experience

BackgroundCardiac Resynchronization Therapy(CRT) is a key treatment for heart failure (HF) in acquired heart disease, but its benefits in adults with congenital heart disease and a systemic right ventricle (sRV) remain unclear. This study aimed to assess whether CRT improves outcomes in patients with sRV. MethodsThis analysis was part of an international, retrospective study of data from 33 centers including patients >18years with transposition of the great arteries (TGA) following atrial switch operation and congenitally corrected TGA (ccTGA). The primary endpoint was overall survival. The secondary endpoint was a composite of death, hospitalization for HF, heart transplant, mechanical support, ventricular tachycardia/ICD therapies. ResultsWe identified 105 out of 1,721 patients(3.5%) who underwent CRT. Median follow-up after CRT implant was 4.6 [1.6-8] years. There was no overall QRS improvement (157{+/-}37 Vs 153{+/-}31 ms; p=0.2), which was limited to those with previous pacing (167{+/-}35 Vs 154{+/-} 28 ms; p=0.002). Following CRT, there was no significant change in B-type natriuretic peptide values, peakVO2, tricuspid regurgitation severity by echocardiography. CRT complications occurred in 10 (9.5%), though there were usually minor. Patients with CRT were propensity-matched to controls according to age, sex, morphology (ccTGA/TGA), presence of complex disease, previous HF admission and sRV dysfunction at baseline. At univariable analysis, CRT (OR 4.02-95% CI:1.48-10.89; p=0.006), older age, and moderate to severe sRV dysfunction at baseline were predictive of death. By multivariable analysis, CRT (OR 2.1-95% CI:1.2-3.8; p=0.008), age (OR 1.03-95% CI:1.01-1.06; p=0.001) and moderate to severe sRV dysfunction (OR 2.5-95% CI:1.3-4.4; p=0.002) were independently associated with poorer outcome. After matching using only patients with subpulmonary ventricle pacing as controls, overall survival was still worse in CRT group (p=0.0057). ConclusionIn this retrospective study in the largest population thus far described with a sRV, CRT implant was not associated to improved survival, even after controlling for key confounders. Further studies with randomization are required to improve the selection of candidates with a sRV most likely to derive benefit from CRT, elucidate the optimal timing, and assess alternative strategies.