The effect of ablation technology on surgical outcomes after the Cox-maze procedure: A propensity analysis

Objectives: Since its introduction in 1987, the Cox-maze procedure has been the gold standard for the surgical treatment of atrial fibrillation. At our institution, this procedure has evolved from the cut-and-sew technique (Cox-maze III procedure) to one using bipolar radiofrequency energy and cryoablation as ablative sources to replace most incisions (Cox-maze IV procedure). This study compared surgical outcomes of patients undergoing the Cox-maze III procedure versus those of patients undergoing the Cox-maze IV procedure by using propensity analysis. Methods: From April 1992 through July 2005, 242 patients underwent the Cox-maze procedure for atrial fibrillation. Of these, 154 patients had the Cox-maze III procedure, and 88 had the Cox-maze IV procedure. Logistic regression analysis was used to identify covariates among 7 baseline patient variables. Using the significant regression coefficients, each patient's propensity score was calculated, allowing selectively matched subgroups of 58 patients each. Operative outcomes were analyzed for differences. Late follow-up was available for 112 (97%) patients. Freedom from atrial fibrillation recurrence and survival was calculated at 1 year by using Kaplan-Meier analysis. Results: The Cox-maze III procedure had significantly longer crossclamp times. There was no significant difference in intensive care unit and hospital stay, 30-day mortality, permanent pacemaker placement, early atrial tachyarrhythmias, late stroke, and survival. Freedom from atrial fibrillation recurrence was greater than 90% in both groups at 1 year. Conclusions: The use of bipolar radiofrequency ablation has simplified the Cox-maze procedure, making it applicable to virtually all patients with atrial fibrillation undergoing concomitant cardiac surgery. The Cox-maze IV procedure produces similar surgical outcomes to the Cox-maze III procedure at 1 year of follow-up.