Predictors and Outcomes of Heart Block During Surgical Stage I Palliation of Single Ventricle Patients: A Report From NPC-QIC

Abstract Background Mortality in single ventricle cohorts remains high with multiple associated factors. The effect of heart block during stage I palliation remains unclear. Objectives To study patient and surgical risks for heart block and its effect on transplant-free 12-month survival in single ventricle patients. Methods Patient, surgical, outcome data and heart block status (transient and permanent) were obtained from the NPC-QIC single-ventricle database. Bivariate analysis was performed comparing patients with and without heart block and multivariable modelling used to identify variables associated with block. One year outcomes were analyzed to identify variables associated with lower 12 month transplant-free survival. Results In total, 1,423 patients were identified, of which 28 (2%) developed heart block (second degree or complete) during their surgical admission. Associated risk factors for block included heterotaxy syndrome (OR 6.4) and atrial flutter/fibrillation (OR 3.8). Patients with heart block had lower 12 month survival though only in patients with complete heart block as opposed to second degree block. At 12 months of age, 39% of heart block patients died and were more likely to experience mortality at 12 months compared to patients without block (OR 4.9, 95%CI 1.4,17.5, p=0.01). Conclusions Though rare, complete heart block following stage I palliation represents an additional risk for poor outcomes among this high risk patient population. Heterotaxy syndrome was the most significant risk factor for development of heart block following stage 1 palliation. The role of transient block on outcomes and potential rescue with long term pacing remains unknown and requires additional study.