Effect of myocardial bridging on preoperative atrial fibrillation and survival in patients with obstructive hypertrophic cardiomyopathy

Background Myocardial bridging (MB) was associated with various arrhythmia forms, however, the relationship between MB and preoperative atrial fibrillation (AF) in obstructive hypertrophic cardiomyopathy (oHCM) remains unknown. Method We recruited 968 consecutive patients with oHCM who underwent surgical myectomy, including 144 patients with MB and 822 patients without MB. Result Patients with MB were much younger (43.6 vs. 48.8 years, p < 0.001), more likely to have palpitation (37.4% vs. 25.5%, p = 0.003), had a lower incidence of hypertension (14.6% vs. 27.9% p = 0.001), a higher prevalence of AF (26.4% vs. 11.5%, p <0.001). Multivariate analysis revealed that the presence of MB was independently associated with AF (Odds ratio [OR] 3.73; 95% Confidential interval [CI] 2.32-5.98, p < 0.001). In subgroup analysis, compared to patients with MB on the middle left anterior descending coronary (LAD), those with MB on the proximal LAD had a higher likelihood to develop AF (OR 4.22; 95% CI 1.40-12.68, p = 0.01). Moreover, MB compression (OR 1.04; 95% CI 1.04-1.08, p = 0.013) and MB length (OR 1.06; 95% CI 1.004-1.11, p = 0.034) were independently associated with a higher prevalence of AF after adjusting for age and left atrial diameter. Of 144 patients with MB, 100 of them underwent unroofing or coronary artery bypass graft. Compared to patients without MB, those with MB had a longer perfusion time (108.5±40.7 vs. 96.7±37.3, p<0.001) and cross-clamp time (75.2±28.3 vs.64.7±26.9, p<0.001). Kaplan-Meier survival curves showed no difference in all-cause death, new-onset AF and composite endpoints between patients with and without MB. Conclusion MB and its location, length, and compression degree were independently associated with an increased risk of preoperative AF in adult oHCM patients, which suggested that whether MB needed surgical treatment during septal myectomy should be considered.