epidemiologic studies have found an association between obesity and atrial fibrillation (4-5% increased risk per each 1-unit inc in BMI), presumably mediated through the association of obesity with several factors which could predispose to atrial fibrillation, including diastolic dysfunction, a pro-inflammatory state, atrial enlargement, abnl autonomic function, and atrial structural and electrical remodeling. a randomized control trial was done in Australia to see if weight reduction would alter the course of atrial fibrillation (doi:10.1001/jama.2013.280521). 150 pts with BMI >27 (mean 33) randomized to intensive wt management (8 weeks of modified very low calorie diet of800-1200 kcal, followed by low glycemic index meals, along with written exercise plan of walking or cycling 45 min 3x/wk) vs control (written and verbal nutrition and exercise advice, with fish oil 3g/d) x 13 months. results (comparing intervention vs control):
–wt loss of 14.3 vs 3.6 kg, waist circumf dec 17cm vs 5 cm, BMI dec 5.6 vs 1.3 units
–biochem markers: hsCRP dec from 2.5 o 1.3 vs 2.3 to 1.9; chol changes not signif, but consistently better with intervention group (inc of HDL and dec in LDL)
–BP: dec 3/2 vs 1/1 mm Hg (significant)
–atrial fib assessment: atrial fib severity score (AFSS: scale of symptomatic afib frequency, duration and global assessment of severity, with range from 3.25 to 30) decreased 11.8 vs 2.6; 7-d ambulatory cardiac monitor found decrease in those with at least one episode of afib from 65% to 21% vs 57% to 56%, total number of episodes dec from 3.3 to 0.62 vs 2.8 to 2.0, total duration of afib from 1176 min to 491 vs 1394 to 1546 min.
–echo showed dec in interventricular septal thickness of 1.1 vs 0.6mm and left atrial area of 3.5 to 1.9 cm2
–of note the intervention group did have more people start metformin, lipid lowering drugs, BP drugs and had less alcohol consumption
so, impressive data that this intervention led to dramatic decreases in atrial fib in overwt people with existing afib. hard to disentangle what helped the most: wt loss or hypertension control or decreased drinking (or even perhaps using metformin: diabetes in recent study increased afib risk 50%, and in the current study those in the intervention group had similar blood sugars as the controls but significantly decreased insulin levels). yet another study that lifestyle interventions help…
geoff