By Cara Pellegrini, MD
Assistant Professor of Medicine, UCSF; Cardiology Division, Electrophysiology Section, San Francisco VA Medical Center
Dr. Pellegrini reports no financial relationships relevant to this field of study.
SOURCE: Pathak RK, et al. Long-term effect of goal-directed weight management in an atrial fibrillation cohort: A long-term follow-up study (LEGACY). J Am Coll Cardiol 2015;65:2159-2169.
Atrial fibrillation (AF) — a condition affecting millions of people — currently has no cure. Symptoms are managed via medications, ablation, and, in select cases, with pacemaker implantation and ablation of the AV node. The rhythm control strategy often leads to disappointing results, with meta-analysis data suggesting only slightly better than half the patients undergoing AF ablation are “free of AF” at just over a year mean follow-up. Antiarrhythmic drug results are generally worse. Further, the risks of procedural complications, drug side effects, and toxicities must be recognized. Recently, there have been several publications from Dr. Sanders and colleagues in Australia examining the effects of weight loss and risk factor management (including blood pressure control, diabetic control, and treatment of sleep apnea) on symptomatic AF burden that have been promising, but follow-up has been short. Their latest effort looks at longer-term follow-up of weight loss and effects of weight fluctuation on AF rhythm control.
The LEGACY study reports on the four-year mean follow-up of 825 obese patients with AF who were offered weight management. Patients were grouped according to degree of weight loss success: group 1 (≥ 10%), group 2 (3-9%), group 3 (< 3%). AF outcomes were measured by 7-day ambulatory monitors. Symptoms were assessed with the well-validated AF severity scale; in addition to weight, blood pressure, metabolic, and inflammatory markers, echocardiographic parameters were followed. Weight loss ≥ 10% was associated with a six-fold greater probability of arrhythmia-free survival compared to the other two groups. At final follow-up, 45.5% of group 1 were free of AF without the aid of ablation or antiarrhythmic medications. Almost double that (86.2%) were AF free with the addition of ablation(s) ± antiarrhythmic drugs (only 10% of patients in group 1 were on an antiarrhythmic at follow-up). Weight loss was associated with a dose response benefit in metabolic and inflammatory markers, blood pressure control, and need for anti-hypertensive medications, and even echocardiographic parameters. For example, left atrial volume fell from 37.6 mL/m2 to 30.9 mL/m2 in group 1. Notably, weight fluctuation of > 5% partially offset the benefit of weight loss, with a two-fold increased risk of arrhythmia recurrence compared to those with < 2% weight fluctuation. The authors conclude long-term sustained weight loss was possible and was associated with a significant reduction in AF burden.
Although obesity has not been proven causative of AF, increasing BMI values have been associated with incrementally higher AF risk. Whether obesity (and weight loss) modulates AF risk directly or via its impact on other cardiovascular risk factors is also unclear. The results of this study and others make clear that weight loss does result in reversal of negative cardiac remodeling, metabolic derangements, and symptomatic AF progression. The magnitude of the impact of weight loss is striking. Although the true AF burden was likely underestimated in this study due to the intermittent nature of the monitoring performed (across all groups), this was not different than many past studies of ablation and antiarrhythmic drug effect. Given the long follow-up duration in this study, weight loss alone compares quite favorably with other strategies for AF rhythm control.
It is important to recognize that participation in a weight management clinic greatly enhanced the likelihood of sustained weight loss in this study. Eighty-four percent of those in the ≥ 10% weight loss group chose to attend this clinic as opposed to 57% in the 3-9% weight loss group and 30% in the < 3% weight loss group. Similar trends were seen for weight fluctuation, with smaller numbers of patients who participated in the clinic showing > 5% weight fluctuation. Thus, the recommendation our patients hear from us should not only be an admonishment to lose weight, but a referral to a program to maximize the patient’s success in this long-term endeavor.
Obviously, weight loss and risk factor modification generally at any point is beneficial. Previous results have shown that weight loss concurrent with AF ablation enhances the results of the ablation. The superiority of the ≥ 10% weight loss group in the “total AF freedom,” which included effect of ablation (performed in similar numbers across groups), medications, and weight loss, echoed that. The tantalizing prospect is the idea that weight loss and general risk factor modification can be a practical long-term strategy alone. In our clinic, we are pushing patients to have their sleep apnea treated and blood pressure controlled prior to consideration of ablation. Perhaps we should be giving more attention to a well-resourced weight loss effort early on as well.