Post-Ablation Recurrence Risk Increases with BMI in Patients with Atrial Fibrillation

Analyses of patient records indicate that obesity increases the risk of recurrence among patients who undergo ablation for atrial fibrillation (AF) but suggests that sustained weight loss can reduce the risk.

Researchers from Intermountain Medical Center Heart Institute in Salt Lake City first pulled records from 1,558 patients who had undergone catheter ablations and remained in the system long enough to provide at least 3 years of follow-up data. They then used body mass index (BMI) information to separate those patients into 4 groups: BMI <20 kg/m², BMI 21-25 kg/m², BMI 26-30 kg/m² and BMI > 30 kg/m².

AF recurrence rates showed a significant positive correlation with BMI. AF recurrence rates rose steadily from 1 group to the next, starting with the BMI <20 kg/m² group and peaking (at nearly 75%) with the BMI >30 kg/m² group (p=0.02). Incidence of heart failure, stroke and death, however, did not follow the same pattern. Stroke rates were statistically similar among all patient groups and death rates, while rising slightly from the BMI <20 kg/m² to the BMI 21-25 kg/m² group, only to decline somewhat thereafter as patients got heavier.

“Lower weight at AF ablation, lowers arrhythmia recurrence risk. However, AF ablation patients that are underweight remain at high risk of other cardiovascular outcomes and the lower arrhythmia outcomes do not result in an observable stroke risk reduction,” wrote the investigators, who presented their findings at the Scientific Sessions of the American Heart Association conference in Orlando.

The second analysis involved 407 AF patients who had a BMI >30 kg/m2 when they underwent ablation at Intermountain. Investigators again divided the patients, this time into 3 groups: those who lost >3% of their baseline bodyweight (141 patients), those who roughly maintained their baseline bodyweight (147 patients) and those who gained >3% of their baseline bodyweight (119 patients).

After 3 years of follow-up, the risk of AF recurrence was significantly higher in patients who maintained their weight (hazard ratio [HR], 1.45; p=0.05) than in those who lost weight. The increased risk did not quite rise to the level of significance in those that gained weight (HR, 1.54; p=0.07).

Researchers also correlated patient weight with the risk of major adverse clinical events and found that the rate of such events increased from 18.4% in those that lost weight at 3 years to 18.6% (HR, 1.32; p=0.29) in those that maintained their weight and 26.5% in those that gained weight (HR, 2.01; p=0.02).

“This study shows one of the most powerful ways to improve outcomes after a cardiac ablation is in the patient's control,” said Jared Bunch, MD, the director of electrophysiology at Intermountain and the lead author of both studies. “In patients who are overweight at the time of their ablation, losing 10 pounds or more leads to significant improvements in the ablation success rates.

“As with all heart conditions, losing weight is only one piece of the puzzle. The patients also have to keep the weight off for up to a year. Patients who quickly gained the weight back or even gained more than they weighed at their ablation had the worst outcomes.”