Evidence guiding cardiac resynchronization therapy (CRT) in adults with congenital heart disease (CHD) and heart failure with reduced ejection fraction (HFrEF) remains limited. A retrospective study published in Heart Rhythm evaluated the association of CRT with mortality, cardiovascular events, and changes in disease severity markers in this population.

The analysis included adults with CHD, biventricular circulation, a systemic left ventricle, and HFrEF who received CRT at Mayo Clinic during the reported study period. New York Heart Association (NYHA) class, peak oxygen consumption, N-terminal pro-B-type natriuretic peptide (NT-proBNP), and left ventricular ejection fraction (LVEF) were assessed before CRT and at 1 year. Intensity of heart failure therapy was assessed using the guideline-directed medical therapy (GDMT) score.

Among 327 patients with CHD and HFrEF, 105 (32%) received CRT. The mean age was 51 ± 15 years, and 68% were male. CRT was associated with a 24% lower risk of mortality (adjusted hazard ratio [HR] 0.76; 95% confidence interval [CI] 0.51-0.97) and a 21% lower risk of cardiovascular events (adjusted HR 0.79; 95% CI 0.63-0.94).

Seventy-one patients (68%) met responder criteria, defined as an absolute LVEF increase of at least 10% with NYHA improvement by at least one class. Higher GDMT score was associated with greater odds of response (adjusted odds ratio 1.28; 95% CI 1.04-1.47). Responders had greater temporal improvement in NYHA class, peak oxygen consumption, NT-proBNP, and lower cardiovascular event risk (unadjusted HR 0.73; 95% CI 0.47-0.99).

These findings support the use of CRT and GDMT for the management of HFrEF in adults with CHD.