Obesity and obstructive sleep apnea (OSA) are strongly associated with atrial fibrillation (AF). Recent studies showed that obesity increases the risk of developing AF by 49% in the general population. Chilukuri et al., therefore did a study to evaluate the effects of obesity and OSA on the efficacy of catheter ablation of AF.

The study was done at John’s Hopkins University hospital and included 118 consecutive patients with drug-refractory AF who underwent catheter ablation. 9 patients were excluded. 79% were men with an average age of 60 years. The mean BMI was 28 kg/m2. Based on the BMI, patients were classified as normal (<25 kg/m2), overweight (≥25 and <30 kg/m2), or obese (≥30 kg/m2). Among the 109 patients, 30 had a normal BMI, 43 were overweight, and the remaining 36 were obese. All patients underwent pulmonary vein (PV) isolation guided by electroanatomical mapping. Electrical isolation was confirmed by a circular multipolar electrode mapping catheter.

Patients were seen for follow up 3 months after the ablation and regularly thereafter. Routine ECGs were obtained at each clinic visit. If asymptomatic AF was detected, it was considered as a true recurrence. Patients were continued on an antiarrhythmic drug for at least 3 months after the ablation. Antiarrhythmic drug was discontinued if patients were free of AF for 3 months. Any episode of symptomatic or asymptomatic atrial tachyarrhythmia (AF, atrial tachycardia, atrial flutter) after the initial 3-month blanking period and lasting 30 seconds or longer was considered as an AF recurrence. Clinical success was defined as at least 90% reduction in AF burden after 3-month blanking period.

The mean follow-up duration was 11 months. Among the 109 patients, 75 patients (69%) met the criteria for clinical success. Thirty-four patients (31%) had a failed outcome after the catheter ablation of AF. Of the 75 patients with clinical success, 25 patients had a normal BMI, 29 patients were overweight, and 21 patients were obese. Among the 34 patients with failed outcome, 15% had a normal BMI, 41% were overweight, and 44% were obese (P = 0.04). 58% of patients with OSA had clinical success as opposed to 77% of patients without OSA (P = 0.036).

On univariate analysis, persistent AF, higher BMI, and presence of OSA were identified as risk factors for failure after catheter ablation of AF. However, on multivariate analysis, only BMI was an independent predictor of failure of catheter ablation of AF (P = 0.03). As a continuous variable, each unit increase in BMI was associated with 11% increase in the probability of failure after catheter ablation of AF.

Conclusion: Results of this prospective study show that obesity, a modifiable risk factor, is an independent predictor of procedural failure after catheter ablation of AF. These findings highlight the importance of treating modifiable risk factors for AF prior to catheter ablation. Whether interventions to decrease the BMI will improve outcome of catheter ablation of AF needs to be evaluated in future studies.

Reference:

Chilukuri K, Dalal D, Gadrey S, Marine JE, Macpherson E, Henrikson CA, Cheng A, Nazarian S, Sinha S, Spragg D, Berger R, Calkins H. A prospective study evaluating the role of obesity and obstructive sleep apnea for outcomes after catheter ablation of atrial fibrillation. J Cardiovasc Electrophysiol. 2010 May;21(5):521-5.