Treatment strategies and prognosis of complete left bundle branch block after transcatheter closure of ventricular septal defect in pediatrics

Background Complete left bundle branch block (CLBBB) is one of the most serious and concerning complications associated with transcatheter closure of perimembranous ventricular septal defect (pmVSD). Management of post procedural CLBBB remains a great challenge for device closure of pmVSD. Objective The aim of the study was to evaluate various treantment strategies and prognosis of CLBBB after transcatheter closure of pmVSD in pediatric patients. Methods A total of 25 pediatric patients diagnosed with CLBBB after transcatheter closure of pmVSD in our institution from January 2010 to December 2023 were retrospectively reviewed. Results The median follow-up time was 6.5 years(range, 0.9-12.8 years). 14 cases were defined as early-onset CLBBB. Among them, 7 underwent early surgical device removal withing 1 month, all restored sinus rhythm. 3 underwent late surgical device removal at 12.9, 10.7, and 3.7 months after CLBBB occurrence, respectively. 2 of them eventually underwent pacemaker implantation, and 1 restored sinus rhythm. The residual 4 cases received corticosteriod therapy, 2 restored sinus rhythm, 1 reverted to left anterior fascicular block, and 1 died of heart failure at day 1 post cardiac resynchronization therapy(CRT). 11 cases were defined as late-onset CLBBB and were all prescribed with corticosteroid therapy as initial treatment. 2 restored sinus rhythm, 1 underwent surgical device removal at 7 months post procedure and recovered to sinus rhythm, and 8 had persistent CLBBB[2 remained normal left ventricular(LV) size and function, 4 had LV enlargement with LV dysfunction, 1 developed cAVB and underwent pacemaker implantation, and 1 underwent cardiac implantation at 3 months post CRT]. Compared with patients who only received corticosteroid therapy or underwent late device removal, patients who underwent early device removal were less likely to experience adverse events [53% (9/17) vs.0% (0/8) , P=0.022]. For patients who did not underwent surgical device removal, patients who were free from adverse events had significantly shorter QRS index[(7.90±0.80) vs.(9.40±1.23) ms/(kg/m2), P=0.032]. Patients with QRS index shorter than 8.29ms/(kg/m2) appeared more likely to response to corticosteroid therapy and less likely to experience poor prognosis. Conclusion Early surgical device removal seems to be associated with favourable prognosis of new-onset CLBBB after pmVSD device closure. Conservative corticosteroid therapy might be an alternative treatment strategy for CLBBB patients with relatively narrow QRS[QRS index＜8.29ms/(kg/m2)].