Major findings: In the present study of extremely obese patients (BMI ≥ 40 kg/m2) undergoing AF CA, sinus rhythm maintenance was only 39% at 1-year follow-up even with the use of class I or III AAD. Patients with non-paroxysmal AF had even lower success rate. Furthermore, there was no significant weight loss, with or without maintenance of sinus rhythm during the 1-year follow-up.
Overweight and obesity are generally defined as BMI 25-29.9, and ≥ 30 kg/m2, respectively. In Europe and North America, over 60% of adults are at least overweight, and of these 20-30% are obese. In the Framingham Heart Study, every unit increase in BMI correlated with a 4-5 % increase in AF diagnosis. The interplay between excess body weight and AF is complex. In addition to its close association with other cardiovascular risks and sleep disordered breathing (SDB), obesity appears to modulate underlying arrhythmogenic substrates,, exacerbating atrial dilatation,, diastolic dysfunction,- inflammation-, fibrosis, and conduction heterogeneity. More recently, the pro-arrhythmic roles of pericardial fat and obesity-associated biomarkers (leptin, adiponection) have been implicated in the pathogenesis of AF.,,
Excess body weight has been shown to negatively impact AF CA outcomes. Winkle et al evaluated AF CA outcomes in 2715 patients, including 129 patients with BMI > 40 kg/m2.15After multiple AF CA procedures, the reported 1-year AF free survival (no AAD) was 67% with an increase in the rate of complications. Sivasambu et al examined AF CA outcomes for 701 patients, including 84 patients with BMI > 40 kg/m2. In this subgroup with BMI > 40 kg/m2 , the 1-year AF free survival after CA was 42%, similar to the results of our current study. Compared to prior publications, the current study population was younger, and had a lower CHA2DS2-VASc score, yet the success of a single AF CA procedure was lower (33%) at 1-year follow-up. This may be due to the more intensive arrhythmia monitoring, the strict definition of single AF CA success, and higher rate of non-paroxysmal AF (74%) in our cohort. The relatively high rates of AF CA procedural complications observed in this study are consistent with complication rates observed by Winkle et al. in patients with BMI ≥ 4015.
Despite advances in mapping, imaging and ablation technologies, the success rates for AF CA remain rather constant for 60-80% and 50-60% in patients with paroxysmal AF and persistent AF, respectively.- Consequently, there has been a growing interest in comprehensive management of AF risk factors including body weight, SDB, and other cardiovascular comorbidities as therapeutic targets for AF management. In the ARREST-AF (Aggressive Risk Factor Reduction Study for Atrial Fibrillation and Implications for the Outcome of Ablation) and LEGACY (Long-Term Effect of Goal Directed Weight Management on an Atrial Fibrillation Cohort) studies, the investigators demonstrated that a structured, physician driven, and goal-directed weight and risk factor management strategy can lead to reduced AF burden and higher AF CA success rates., In the LEGACY study, sustained > 10% weight loss was associated with lower AF recurrence, compared to those with < 3% weight loss, indicating a dose-dependent effect of weight loss on AF burden.
In the sub-analysis of the LEGACY cohort, the investigators also observed regression of persistent AF to either paroxysmal or no AF among patients with more substantial weight loss and, 52% of patients with AF and > 10% weight loss achieved no AF after the mean 48-month follow-up.
Lastly, the lack of weight loss even among patients with successful sinus rhythm maintenance is discouraging since one of the incentives for the patient and the physician to pursue AF CA in this cohort is that with long-term sinus rhythm maintenance, the patient will feel more motivated to pursue active lifestyle and to achieve sustained weight loss.
Given the incomplete understanding of AF pathogenesis, the increased risk of complications and the low success of AF CA in extreme obesity, electrophysiologists should incorporate other strategies for managing atrial arrhythmias before considering CA, such as enrollment and active participation in a monitored weight reduction program, and perhaps consideration of bariatric surgical options. Once the patient demonstrates successful lifestyle changes and sustained weight loss, then AF CA may be considered and would likely have greater success.