Background: This study aims to evaluate the long-term rhythm outcomes of the Cox-Maze IV procedure in patients undergoing complex cardiac surgery, where atrial fibrillation ablation was performed as a second, third, or fourth-and-beyond concomitant operation.

Methods: Between October 2018 and February 2025, a total of 71 patients (24 males, 47 females; mean age: 59±10 years; range, 36 to 80 years) who underwent a complete Cox-Maze IV lesion set and achieved at least six months of rhythm follow-up were retrospectively analyzed. The patients were grouped by the number of concomitant cardiac procedures performed: Group 1 (one procedure, n=16), Group 2 (two procedures, n=43), and Group 3 (?3 procedures, n=12). Rhythm monitoring included 24-h Holter and pacemaker interrogation.

Results: At a mean follow-up of 26±2 months, overall freedom rate from atrial tachyarrhythmias was 88.7%. Group-specific freedom rate from atrial tachyarrhythmias at 36 months was as follows: 100% in Group 1, 80.0% in Group 2, and 87.5% in Group 3. No significant intergroup differences were observed. Pacemaker implantation was needed in 7.0% of the patients. Higher procedural complexity did not adversely affect rhythm outcomes.

Conclusion: Our study results suggest that Cox-Maze IV provides excellent long-term rhythm control even in complex cardiac surgeries involving multiple concomitant procedures. The effectiveness of the procedure appears to be preserved across increasing surgical complexity, supporting its broader application.

Keywords : Atrial fibrillation, cardiac surgery, Cox-Maze IV, rhythm outcomes, surgical ablation