Weight loss in obese patients with longstanding persistent atrial fibrillation undergoing catheter ablation: Is it worth the trouble?
Atrial fibrillation (AF) is the most common cardiac rhythm disorder, impacting over 33 million people worldwide.1 Besides age, there are several other risk factors that are associated with this condition. These include male gender, obesity, sleep apnea, hypertension, excess alcohol use, etc. Obesity, in particular, has been found to be a strong and independent predictor of AF.2 Hence, there is growing interest in developing strategies to address this and other common risk factors in the AF population. The first comprehensive attempt to address multiple risk factors in AF patients was made by Pathak et al. in a physician‐directed out patient clinic model.3 Using this approach, these investigators were able to modify favorably obesity, sleep apnea, hypertension, diabetes, cholesterol, alcohol consumption, and smoking in their AF patients, which translated into improved AF ablation outcomes. These investigators subsequently conducted a second larger observational study in which they were able to demonstrate a dose–response relationship between weight loss and long‐term maintenance of sinus rhythm.4 In this study, it was interesting to note that the beneficial effects of weight loss were seen regardless of the AF type and/or the management strategy. Thus, patients with both paroxysmal and nonparoxysmal forms of AF, who were able to achieve sustained weight loss, were more likely to maintain sinus rhythm regardless of the management strategy (conservative vs. aggressive). These observations suggest that weight loss affects the mechanisms underlying initiation and maintenance of AF. However, exactly how that happens remains unclear. In both animal models and human subjects, obesity has been found to cause disproportionate accumulation of epicardial adipose tissue.5 Epicardial fat has been shown to promote localized inflammation and fibrosis that, in turn, may lead to adverse atrial electrophysiologic remodeling and AF.7 Successful weight loss in obese subjects can reverse such adverse remodeling.8 This suggests that weight loss may be able to affect favorably the underlying AF substrate. If so, this has implications for the beneficial role of obesity management in nonparoxysmal forms of AF where substrate abnormalities are considered to be the predominant mechanism underlying the arrhythmia.9 While data from observational studies suggest that weight loss promotes sinus rhythm in nonparoxysmal forms of AF, it remains unclear whether patients with longstanding persistent (LSP) AF were included in these series.3 Patients with LSP AF have the worst arrhythmia‐free survival after catheter ablation.10 This has been attributed to the presumably extensive atrial substrate abnormalities in these patients.9 Since weight loss favorably alters the underlying atrial substrate, it can be posited that in patients with LSP AF it should enhance the success of catheter ablation. There is, however, paucity of data assessing the role of weight loss in improving ablation outcomes in patients with LSP AF. Thus, the study by Mohanty et al. in this issue of the journal is indeed timely.11
In this observational series, the authors enrolled 90 consecutive patients with LSP AF undergoing catheter ablation into a weight loss program through diet control and exercise. Fifty‐eight patients agreed to participate in the program and 32 declined. The latter served as the control group. As per study design, ablation was performed ∼1 year after enrollment in order to allow enrolled patients to achieve adequate weight loss. The goal was to achieve ≥10% reduction in weight within 3 months of enrollment and sustain it till the ablation procedure. Patients in the intervention arm completed individual counseling sessions with dieticians, received personalized diet plans, were requested to perform moderate intensity exercise for 150 minutes/week, and were asked to maintain a daily diet and activity diary.