Congenital: Heart blockHeart block following stage 1 palliation of hypoplastic left heart syndrome

ObjectivesPublicly available data from the Pediatric Heart Network's Single Ventricle Reconstruction Trial was analyzed to determine the prevalence, timing, risk factors for, and impact of second- and third-degree heart block (HB) on outcomes in patients who underwent stage 1 palliation (S1P) for hypoplastic left heart syndrome (HLHS).MethodsThe presence and date of onset of post-S1P HB occurring within the first year of life, potential risk factors for HB, and factors known to predict poor outcomes after S1P were extracted. Multivariable logistic and Cox regression analyses were performed to identify risk factors for HB and to determine the effect of HB on 3-year transplantation-free survival.ResultsAmong the 549 patients in the cohort, 33 (6%) developed HB after S1P. The median interval between S1P and HB was 8 days (interquartile range, 0-133 days). Regression analysis showed that tricuspid valve repair during S1P and obstruction of pulmonary venous drainage requiring pre-S1P intervention were independently associated with HB (adjusted odds ratio [aOR], 11.6, 95% confidence interval [CI] 3.3-40; P < .001 and aOR, 5.1; 95% CI, 1.3-20.6; P = .02, respectively). Transplantation-free survival at 3 years was lower for those with HB (39% vs 65%; P = .004). HB remained associated with transplantation-free survival after controlling for known risk factors (adjusted hazard ratio, 3.1; 95% CI, 1.9-5.0; P < .001). Nine children (27%) had a pacemaker implanted, and 7 of these children (78%) died or underwent heart transplantation.ConclusionsHB after S1P is rare but heralds a poor outcome. Careful monitoring of these patients is recommended given their significantly increased risks of death and heart transplantation.