AIMS: Lesion of the atrioventricular conduction system is a well known adverse effect of alcohol septal ablation (ASA) in patients with obstructive hypertrophic cardiomyopathy (HCM). We assessed the atrioventricular conduction at long-term follow-up after ASA. METHODS: In patients with a pacemaker implanted for high-grade atrioventricular block after ASA, the atrioventricular conduction was assessed prospectively by ECGs and 48-h Holter recordings. In the remaining patients, the atrioventricular conduction was analysed retrospectively for comparison. RESULTS: A total of 24 (28%) of 87 patients with obstructive HCM without a pacemaker at baseline had a pacemaker implanted due to high-grade atrioventricular block after ASA. Ten of these patients were not available for follow-up. Holter recordings in the remaining 14 patients revealed normalized atrioventricular conduction in 6 patients 6.2 years (range 2.1-9.4) after ASA. Patients with high-grade atrioventricular block at follow-up had longer PR intervals at baseline [205 ms (200-230)] than the rest of the cohort [180 ms (140-200), P = 0.004] and a higher incidence of acute complete heart block (63 vs. 15%; P = 0.007) during ASA. A PR interval of at least 200 ms at baseline was associated with higher prevalence of high-grade atrioventricular block at follow-up (30 vs. 2%; P = 0.0013). The incidence of late-onset complete heart block was 1.5% per year after ASA. CONCLUSION: We found normalized atrioventricular conduction at long-term follow-up, suggesting recovery in 6 of 14 patients with a pacemaker implanted in relation to ASA. Permanent atrioventricular conduction abnormalities were associated with baseline PR intervals of at least 200 ms and acute persistent complete heart block during ASA.
Journal of Cardiovascular Medicine (hagerstown), 2014, Vol 15, Issue 3, p. 214-221