Introduction
Atrial fibrillation (AF) is the most common cardiac arrhythmia, with a prevalence of 2.1% in people aged more than 65 years, with the highest prevalence in people aged more than 80 years [1]. The prevalence of AF is expected to double by 2050 [2]. The occurrence of AF is associated with age, sex, and, most importantly, cardiac disease. Fifty percent of patients undergoing mitral valve surgery present with AF [3], as do 1% to 6% of patients undergoing coronary artery bypass grafting or aortic valve surgery [4].
Several large studies, including the Framingham study, have shown that AF is associated with an increased risk for mortality and morbidity [5,6]. In the past decade, studies have suggested that patients who present for cardiac surgery with a significant history of AF have reduced survival over time if AF is left untreated [4,7]. Other studies have also found that patients who present with AF have worse perioperative outcomes, including a higher incidence of thomboembolic events like stroke and congestive heart failure [8-10].
The Cox maze procedure was originally designed in 1987 as a concomitant procedure for the treatment of AF in patients undergoing MVS [11]. After several iterations, the Cox-Maze IV procedure was introduced in 2002 [12]. The Cox Maze IV simplified the original procedure by replacing most of the “cut and sew” atrial incisions of the lesion set with linear lines of ablation, making the operation technically easier and faster to perform. Despite the proven success of the Cox-Maze procedure, referring physicians and cardiac surgeons remain somewhat reluctant to adopt the procedure for surgical ablation of AF. Gammie and colleagues published a study based on the Society of Thoracic Surgeons’ database, which demonstrated that only 38% of patients presenting for cardiac surgery while experiencing AF underwent any type of corrective surgical ablation concomitantly with a valve or coronary bypass surgery [13]. The surgical complexity and predicted operative risk are major variables in the decision of whether to perform surgical ablation for AF at the time of other cardiac procedures, because there is a general perception that surgical ablation significantly increases the complexity, operating times and therefore risks for perioperative complications. Currently, no risk models are available for concomitant arrhythmia surgery; thus, the extent of the additional associated risk has been poorly defined. In addition the level of training required to perform surgical ablation and a lack of recognition of the clinical importance of AF may also contribute to the relatively low uptake of the procedure in clinical practice.
The treatment of elderly patients with AF remains a challenge due to concurrent morbidities and age-related physiological changes. Anticoagulation therapies recommended to prevent the thromboembolic events associated with AF also have a greater risk of major bleeding complications in elderly patients. The number of elderly patients is increasing and this is reflected in surgical practice with more patients undergoing cardiac surgery in the last 15 years [14]. Very few studies have examined the efficacy of surgical AF ablation in elderly patients. As a result, the purpose of this study was to evaluate the outcomes of concurrent Cox maze procedures in elderly patients (aged 70 years) who undergo high risk cardiac surgery (i.e. more than 2 additional concomitant procedures). We hypothesized that a concurrent Cox maze procedure does not worsen outcomes in elderly patients undergoing high-risk cardiac surgery.