Cardiac resynchronization therapy in adults with structural congenital heart disease and chronic heart failure

Evidence for CRT in adults with congenital heart disease (ACHD) and chronic heart failure is limited, with recommendations for its use extrapolated from the population with structurally normal hearts. This retrospective observational study investigates the efficacy of CRT in this heterogenous group, discussing factors predicting response to CRT.

Twenty-seven patients with structural ACHD who underwent CRT insertion or upgrade at a tertiary center in the United Kingdom were retrospectively studied. The primary outcome measure was clinical response to CRT, defined as improvement of NYHA class and/or improvement in systemic ventricular ejection fraction by one category. Secondary outcomes included change in QRS duration and adverse events.

Thirty-seven percent of patients had a systemic right ventricle (sRV). RBBB was the commonest baseline QRS morphology (40.7%) despite this being an unfavorable characteristic for CRT. Overall, positive response to CRT was demonstrated in 18 patients (66.7%). NYHA class improved in 55.5% following CRT (p = .001) and 40.7% showed improvement in systemic ventricular ejection fraction (p = .118). There were no baseline characteristics that predicted response to CRT, and electrocardiographic measures such as QRS shortening post-CRT was not associated with positive response. Good response rates (60.0%) were demonstrated in those with sRV.

CRT is efficacious in structural ACHD including in those who do not meet conventional criteria. Extrapolation of recommendations from adults with structurally normal hearts may be inappropriate. Future research should focus on improving patient selection for CRT, for example using techniques to better quantify mechanical dysynchrony and intra-procedural electrical activation mapping in these complex patients.