Credits:Original Citation :Cha YM, Friedman PA, Asirvathan SJ, Shen WK, Munger TM, Rea RF, Brady PA, Jahangir A, Monahan KH, Hodge DO, Meverden RA, Gersh BJ, Hammill SC, Packer DL. Catheter ablation for atrial fibrillation in patients with obesity. Circulation.2008; 117:2583-290.
Reviewed by : John V. Wylie, Jr., MD and Mark E. Josephson, MD
Harvard-Thorndike Electrophysiology Institute, Cardiovascular Division,Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
Address for Correspondence:John V. Wylie, Jr., MD,Division of Cardiology,Beth Israel Deaconess Medical Center,185 Pilgrim Road, Baker 4,Boston, MA, 02215 USA.
doi : 10.4022/jafib.v1i1.404
Obesity is a risk factor for atrial fibrillation (AF) and
common comorbid conditions such as hypertension, sleep apnea, and structural
heart disease. This study was designed to determine whether catheter ablation
of AF can be performed safely and effectively in obese and overweight patients
compared with patients with normal body weight.
A cohort of 523 patients with symptomatic AF undergoing
radiofrequency ablation at a single institution was included in this study.
Body weight was determined and patients were stratified by body mass index into
three groups: lean (BMI < 25 kg/m2), overweight (BMI 25-29.9 kg/m2)
and obese (BMI ≥ 30 kg/m2). Two techniques for atrial fibrillation
ablation were employed: 298 patients underwent pulmonary vein ostial ablation
with a 5mm tip ablation catheter and 222 patients underwent wide-area
circumferential ablation outside the pulmonary vein ostia with an 8mm tip
ablation catheter. Patients in this second group also underwent creation of
linear lesions and ablation of focal triggers of AF identified during
Patients were followed up with a 24-hour Holter monitor 3
months after the ablation. Follow-up after that time
was performed by telephone, annual questionnaires, and with
intermittent monitoring, though the method and timing of monitoring is
not well-described. Quality of life questionnaires were
administered 3 and 12 months after ablation. Outcomes are reported at 12 and
24 months after ablation but Kaplan-Meier curves are not provided.
The majority of patients (58%) had paroxysmal AF. Only 18%
of patients were classified as lean, while 44% were overweight and 38% were
obese. Patients with higher BMI were younger, more likely to have persistent
AF, hypertension, diabetes, structural heart disease, left atrial enlargement,
and sleep apnea. Despite the increased prevalence of these comorbidities, no
significant difference in the rate of freedom from AF was seen among the groups
at the 12-month and 24-month follow up points. At the 24 months, 74% of lean,
73% of overweight, and 69% of obese patients were free of AF. Significantly
more obese patients (48%) were lost to follow-up, which is a limitation of the
study. All groups had a significant improvement in quality of life scores at
the 12-month follow-up visit, and improvement in these scores was associated
with maintenance of sinus rhythm. Obese patients had similar fluoroscopy times
during the procedure, but radiation exposure was nearly triple in obese
patients compared with lean patients (1.97 Gy vs. 0.69 Gy). Serious
complication rates were moderate (5%) but similar across different BMI classes.
Many patients with AF are obese, and this retrospective
cohort study suggests that radiofrequency ablation is equally efficacious for
patients across different body weights. One important consideration when
performing ablation in obese patients is that radiation dose is markedly
increased due to the nonlinear relationship of radiation dose to body size.
This must be a consideration when discussing ablation procedures with patients,
particularly if repeat procedures (performed in 17% of patients in this study)
may be necessary. The outcomes reported in this study are primarily based on
patient-reported symptoms and routine ambulatory monitoring was not performed
after 3 months. Since asymptomatic AF may be more common after ablation, the method
of symptomatic outcome reporting may significantly overestimate success rates.
The results are also reported on a monthly basis and cumulative success rates
are not reported. It is unclear whether these factors may interact with
obesity (for instance, if obese patients had more asymptomatic AF) to limit the
results of this study. Further research on this topic may be required.