Background: Cardiac resynchronization therapy (CRT) is an important therapeutic option in selected pediatric and congenital heart disease (CHD) patients with reduced systemic ventricular (SV) ejection fraction (EF). However, the identification of optimal responders is challenging. Objective: To identify predictors of response to CRT in children and CHD patients at 5 large quaternary referral centers. Methods: Patients were <21 years or had CHD; had SVEF <45%; symptomatic heart failure; and significant electrical dyssynchrony prior to CRT. Primary outcome was defined as an ordinal response at 6/12months: (1) Improved EF [≥5%], (2) Unchanged SVEF, (3) Worse SVEF. Secondary outcome utilized a propensity score-matched control cohort. Response to CRT was defined using longitudinal trajectory of SVEF up to latest follow-up. Results: In total, 167 eligible CRT recipients were identified across the 5 centers. 150 had comprehensive data at 6/12months: 96(64%) with improved SVEF, 26(17%) unchanged, 28(19%) worsened. Mean increase in SVEF was 11% [IQR 3-21%]. On univariable ordinal regression, lower SVEF (p=0.013), biventricular circulation (p=0.022), systemic LV (p=0.021), and conduction delay to lateral wall of SV (p=0.01) were associated with positive response. For assessment of secondary outcome, 324 controls were identified. Mean follow-up 4.2(±3.7) yrs. Almost all subgroups demonstrated improved SVEF trend with CRT, except those with systemic RV (p=0.69) or without prior single site pacemaker (p=0.20). Conclusion: CRT in children and CHD patients frequently results in an improvement in SVEF. Those with lower SVEF, conduction delay to lateral wall of the SV and those with systemic LV are most likely to respond.

The authors have declared no competing interest.

This was a retrospective study

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