[Risk factors and prognosis of heart block after transcatheter closure of perimembranous ventricular septal defect in children].

Objective: To identify risk factors for and evaluate the prognosis of heart block in children following transcatheter closure of perimembranous ventricular septal defect (pmVSD). Methods: This retrospective cohort study included 1 427 children with pmVSD who underwent successful transcatheter closure between June 2002 and August 2023 at Shandong Provincial Hospital Affiliated to Shandong First Medical University, with a minimum follow-up of 1 year. Demographic characteristics, preprocedural evaluations, procedural details and postprocedural follow-up data were analyzed. Patients were categorized into groups with or without postprocedural heart block. The heart block patients were further divided into recovery or persistence groups according to conduction status at the last follow-up. Clinical characteristics, defect anatomy, device parameters and procedural details were compared by independent-samples t-test, χ² test or Fisher exact test. Multivariable Logistic regression was used to identify independent risk factors for the occurrence and persistence of heart block. Results: Of the 1 427 patients, there were 709 males and 718 females, with the age of (4.4±2.6) years and weight of (18.5±8.6) kg. A total of 295 patients (20.7%) developed postprocedural heart block. Among them, the most common type was incomplete right bundle branch block in 179 patients (60.7%), followed by complete right bundle branch block in 52 patients (17.6%). A total of 33 patients were severe heart block, including 5 patients with complete atrioventricular block (cAVB) and 28 patients with complete left bundle branch block (CLBBB). Of the 295 patients , 290 patients (98.3%) were early-onset, and 5 patients (1.7%) were late-onset. Nine patients developed recurrent heart block. Multivariable Logistic regression identified the following independent risk factors for block occurrence: use of thin-waist occluders (OR=1.85, 95%CI 1.12-3.04, P=0.016), higher occluder-to-defect diameter ratio (OR=1.90, 95%CI 1.38-2.62, P<0.001) and longer procedure duration (OR=1.01, 95%CI 1.00-1.01, P<0.001). Deployment of the occluder's left disk within the aneurysmal tissue was protective (OR=0.57, 95%CI 0.37-0.89, P=0.014). No independent predictors were identified for block persistence. The follow-up time for the 295 patients with heart block was 6.8 (4.3, 10.2) years. Normal conduction was recovered in 161 patients but persistent in 134 patients, including 129 patients with early-onset (8 patients recurrent) and 5 patients with late-onset. Four patients with CLBBB recovered normal conduction after occlude removal. Conclusions: Higher occlude-to-defect ratio, use of thin-waist occluders and longer procedural duration increase the risk of heart block following transcatheter closure of pmVSD in children. In contrast, deploying the occluder's left disk within the aneurysmal tissue may reduce the risk. The prognosis of postprocedural heart block is generally favorable, but vigilant long-term follow-up is warranted due to the possibilities of late-onset or recurrent block in a minority of patients.