Surgical volume and outcomes of surgical ablation for atrial fibrillation: a nationwide population-based cohort study

BACKGROUND: Atrial fibrillation is the most common cardiac arrythmia and causes many complications. Sinus rhythm restoration could reduce late mortality of atrial fibrillation patients. The Maze procedure is the gold standard for surgical ablation of atrial fibrillation. Higher surgical volume has been documented with favorable outcomes of various cardiac procedures such as mitral valve surgery and aortic valve replacement. We aimed to determine the volume-outcome relationship (i.e., association between surgical volume and outcomes) for the concomitant Maze procedure during major cardiac surgeries. METHODS: This nationwide population-based cohort study retrieved data from the Taiwan National Health Insurance Research Database. Adult patients undergoing concomitant Maze procedures during 2010-2017 were identified; consequently, 2666 patients were classified into four subgroups based on hospital cumulative surgery volumes. In-hospital outcomes and late outcomes during follow-up were analyzed. Logistic regression and Cox proportional hazards model were used to analyze the volume-outcome relationship. RESULTS: Patients undergoing Maze procedures at lower-volume hospitals tended to be frailer and had higher comorbidity scores. Patients in the highest-volume hospitals had a lower risk of in-hospital mortality than those in the lowest-volume hospitals [adjusted odds ratio, 0.30; 95% confidence interval (CI), 0.15-0.61; P < 0.001]. Patients in the highest-volume hospitals had lower rates of late mortality than those in the lowest-volume hospitals, including all-cause mortality [adjusted hazard ratio (aHR) 0.53; 95% CI 0.40-0.68; P < 0.001] and all-cause mortality after discharge (aHR 0.60; 95% CI 0.44-0.80; P < 0.001). CONCLUSIONS: A positive hospital volume-outcome relationship for concomitant Maze procedures was demonstrated for in-hospital and late follow-up mortality. The consequence may be attributed to physician skill/experience, experienced multidisciplinary teams, and comprehensive care processes. We suggest referring patients with frailty or those requiring complicated cardiac surgeries to high-volume hospitals to improve clinical outcomes. TRIAL REGISTRATION: the institutional review board of Chang Gung Memorial Hospital approved all data usage and the study protocol (registration number: 202100151B0C502).