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.