Is Bypassing Traditional Weight-Loss the Answer for Atrial Fibrillation?

Cardiovascular risk factors have been recognized to contribute to abnormal atrial remodeling leading to increased incident atrial fibrillation (AF) as well as AF progression and poorer outcomes with rhythm control strategies.1 There has been an increasing focus on obesity as a modifiable risk factor contributing to the AF substrate because of its rising prevalence.2 In an individual with metabolic syndrome, a stepwise increase in the AF risk has been described with increasing number of risk components including impaired fasting glucose, elevated blood pressure, increased waist circumference, and dyslipidemia.3 Fortunately, the abnormal AF substrate has been shown to be partially reversible when the underlying risk factors are aggressively targeted.4–8 The risk factor management clinic targeted weight-loss of at least 10% with dietary control, frequent moderate-intensity exercise up to 250 min/wk, blood pressure <130/80 mm Hg, glycaemic control with HbA1c ≤6.5%, active screening for obstructive sleep apnea with continuous positive airway pressure therapy to achieve apnea-hypopnea index <5/h, complete smoking cessation, alcohol consumption to <30 g/wk and lipid management.9 These strategies have resulted in reducing AF burden and symptoms, improving catheter ablation outcomes, and reversal of AF accompanied by beneficial reverse cardiac remodeling.4–8 Notably, the subjects included in these studies have mean body mass index (BMI) in the range of 30 to 34 kg/m2. Data remain lacking in those who are morbidly obese (BMI ≥40 kg/m2) and with regards to alternate weightloss strategy. A single-center observational study in obese individuals with a BMI of 38±4 kg/m2 and long-standing persistent AF failed to observe improvement in AF symptoms or burden despite significant weight-loss and raised the possibility of a point of no return in terms of the impact of weight-loss.10 It is in this context that the series of articles presented by Donnellan et al11,12 on the role of bariatric surgery (BS) on the outcomes of AF ablation in morbidly obese individuals further advances our knowledge on the importance of risk factor management in the spectrum of obese individuals undergoing ablation. In their first report, they present data on 239 patients who were morbidly obese and underwent AF ablation (defined as BMI ≥40 or ≥35 kg/m2 with obesity-related complications).11 Of these 51 had undergone BS before ablation. At a mean follow-up of 36 months after ablation, 20% who had undergone BS compared to 61% without BS had recurrent arrhythmia (P<0.0001).11 These results are further expanded using the same cohort in a study published in the Journal.12 In this article, the authors compared in a 2:1 manner the 51 morbidly obese patients who underwent BS with ageand gender-matched 102 nonobese and 102 morbidly obese patients without prior BS who underwent catheter ablation around the same time period. The BMI between the 3 groups was significantly different: 25.6±3 kg/m2 in the nonobese EDITORIAL