The Cox maze III operation (sometimes called the “cut-and-sew” maze operation) is a complex surgical procedure for the control of AF, and is extensive and time consuming, requires great surgical skill. Our initial concern was unsafe, especially the potentially dangerous for bleeding, to perform the maze III procedure concomitant valve surgery because of the significantly increased cardiopulmonary bypass and aortic cross-clamp time. In this study, we described the experience of 66 patients with persistent or long-standing persistent AF who underwent maze III procedure combined with valve surgery over a 3-year period. The population had a median age of 54 years. The in-hospital mortality was 3%, suggesting that the Cox maze III procedure combined with valve surgery is both feasible and safe in a carefully selected population. Our in-hospital mortality was in keeping with previous reports describing the operation of maze III procedure combined with valve surgery[3,5,9,10,11]. Despite the increased duration of CPB and aortic cross-clamp time, the incidence of major postoperative complications, including bleeding, renal failure, stroke and SWI, were low in this study. The results could be attributed to the fact that the improvement of modern intro-operative myocardial protection strategy. In this population, no one was complicated by heart failure, required IABP or ECMO support. However, the cohort in this study was low risk (mean age 54.2 years, mean LVEF 55.7%), which might have influenced the results. So we should be cautious when considering the possibility of maze III procedure plus valve surgery in those high risk patients, such as elderly, lower LVEF.
In this trial, we found that the rate of freedom from atrial fibrillation in 24 months after Cox maze III procedure was over 90%. In recent years, new technologies and approaches to surgical AF ablation have been evolved to simplified lesion sets and shorten the time, but the issue of ensuring completely transmural lesions remains unresolved. In a randomized multicenter trial involving patients with persistent or long-standing persistent AF who were undergoing mitral-valve surgery, Gillinov AM et al[2] reported the freedom from AF in the first year after surgery was 63.2% in the ablation procedures (pulmonary-vein isolation or biatrial maze procedure) group. The “cut-and-sew” maze III operation can assure the transmurality and eliminates this concern. Stulak et al[3]reported the patients undergoing the Cox maze III procedure concurrent with isolated mitral valve surgery resulted in significantly greater freedom from AF without antiarrhythmic medication compared with any other procedure for AF ablation within 1 year postoperatively (87% vs 70%, P = 0.04) and after 5 years postoperatively (75% vs 52%, P = 0.03). Many of the studies have shown for both catheter and surgical ablation that left atrial enlargement is a predictor of failure[12]. Ishii Y [13] reported preoperative LAD of ≧58.0mm was a significant risk factor for an AF recurrence after AF surgery, the AF cure rates were 85%, 59%, and 42% at 1, 5, and 10 years after the AF surgery in the population who had an LAD = 64.2 mm (range 58.0–82.0 mm). In the present trial, the mean diameter of preoperative left atrial was 53.1mm, and the mean LVEF was 55.7%. These factors might have improved the likelihood of ablation success in our study.
The need for PPI after operation remains a matter of concern for the Cox maze III procedure. In our study, 2 of 3 patients received PPI before discharge converted sinus rhythm at 3 months postoperatively, meanwhile one patient with junctional rhythm at discharge required PPI. The results related to the need for PPI in the literatures were different. In a case-matched study[14], Stulak et al found that new PPI was required in significantly more patients in the radiofrequency group than in the cut and sew group (25% versus 5%). In a single-center cohort of Cox maze III procedure concomitant cardiac surgery, Fernando A et al[11] found that the PPI was required in 3.6% of total, and 18.2% of those with three associated valve procedures. A cumulative meta-analysis of randomized controlled trials (RCT) on clinical outcomes of surgical ablation versus no ablative treatment in all patients with cardiac surgery demonstrated that there were no significant differences between surgical ablation versus no ablation in terms of pacemaker implantations[15]. One reason that new permanent pacemakers are required following a maze procedure is premature pacemaker implantation for a temporary junctional rhythm immediately postoperatively[16]. In the present study, the rate of junctional rhythm in the immediate postoperative period following maze procedure was 7.9% (5/64) overall.
The following factors limited this study. First, it was a retrospective trial and possessed all the inherent limitations of this type of study design. Second, the rhythm was evaluated mainly on the basis of 12-lead ECG and partly by 24-hour Holter ECG, which might tend to overestimate the clinical success, compared with long-term monitoring. The HRS guidelines (2012) recommend that a 1- to 7-day Holter monitoring is an effective way to identify frequent asymptomatic recurrences of AF. We have begun to follow patients with 7-day Holter monitoring during follow-up in the current era. Finally, our follow-up data were not available for all patients, and had a small sample size. A larger sample and longer follow-up are required for a future study. This is just the beginning of our study and will continue to do better.