BACKGROUND: Cardiac resynchronization therapy (CRT) is an important therapeutic option in selected pediatric patients and patients with congenital heart disease with reduced systemic ventricular ejection fraction (SVEF). However, the identification of optimal responders is challenging. This study aimed to identify predictors of response to CRT in children and patients with congenital heart disease at 5 large quaternary referral centers. METHODS: Patients were aged <21 or had congenital heart disease and had SVEF <45%, symptomatic heart failure, and significant electrical dyssynchrony before CRT. Primary outcome was defined as an ordinal response at 6 of 12 months: (1) improved SVEF (≥5%), (2) unchanged SVEF, and (3) worse SVEF. Secondary outcome utilized a propensity score–matched control cohort. Response to CRT was defined using the longitudinal trajectory of SVEF up to the latest follow-up. RESULTS: In total, 167 eligible CRT recipients were identified across the 5 centers; 150 had comprehensive data at 6 of 12 months: 96 (64%) with improved SVEF, 26 (17%) unchanged, and 28 (19%) worsened. Mean increase in SVEF was 11% (interquartile range, 3%–21%). On univariable ordinal regression, lower SVEF ( P =0.013), biventricular circulation ( P =0.022), systemic left ventricle ( P =0.021), and conduction delay to the lateral wall of the systemic ventricle ( P =0.01) were associated with a positive response. For the assessment of the secondary outcome, 324 controls were identified. Median follow-up is 5.1 (interquartile range, 2.0–8.6) years. Almost all subgroups demonstrated improved SVEF trend with CRT, except those with systemic right ventricle ( P =0.69) or without prior single-site pacemaker ( P =0.20). CONCLUSIONS: CRT in children and patients with congenital heart disease frequently results in an improvement in SVEF. Those with lower SVEF, conduction delay to the lateral wall of the systemic ventricle, and those with a systemic left ventricle are most likely to respond.
Chubb et al. (Tue,) studied this question.