Obesity and AF: A Dose-dependent Relationship

Prevalence of atrial fibrillation in increasing worldwide. There is a clear relationship between obesity and AF; one estimate is the linkage accounts for ~20% of burden of AF(3). Mechanism may be indirect (increased prevalence of sleep apnea and hypertension in obese patients) or direct (metabolic and hormonal consequences of obesity). This study attempted to fully characterize this association and to determine the excess risk for AF conferred with incremental increases in obesity.

Jan 2012. Search terms: obesity, overweight, body mass index (BMI), arrhythmia, and atrial fibrillation. Included cross-sectional, case-control, or cohort studies that allowed for assessment between BMI and AF. Outcome: incident AF, post-operative AF, or post-ablation AF. 51 studies included (n= 626,603): 23 incident AF, 12 post-operative AF, 16 post-ablation AF.

Obesity and Incident AF (cohort studies): mean age 59 years, 53% female, and mean follow-up 10 months. 29% greater risk of developing AF for every 5-U increase in BMI (95% CI: 1.23 to 1.36). Significant heterogeneity due to between-study differences (I2 statistic 54.7%), with some evidence of smaller estimates in studies from North America (p = 0.02). No significant publication bias

Obesity and Incident AF (case-control studies): Mean age 60 years, mean 43% female. 19% risk of AF for every 5-U increase in BMI (95% CI: 1.13 to 1.26). Significant heterogeneity due to between-study differences (I2 statistic 80%), with again some evidence of smaller estimates in studies from North America (p

Obesity and post-operative AF: Mean age 64 years, mean 26% female. 10% greater excess risk of post-operative AF for every 5-U increase in BMI (95% CI: 1.04 to 1.17). Significant heterogeneity due to between-study differences (I2 statistic 82.9%), with some evidence of larger estimates in studies from Asia (p = 0.003). No significant publication bias.

Obesity and post-ablation AF: Mean age 56 years, mean 30% female, mean follow-up 20 months. 13% greater excess risk of recurrent AF post-ablation for every 5-U increase in BMI (95% CI: 1.06 to 1.22). Significant heterogeneity due to differences between studies (I2 statistic 78.6%). No significant publication bias.

Summary For every 5-U increase in BMI, there were 10% to 29% excess risks of incident, post-operative, and post-ablation AF. Limitations: Estimates obtained may be overestimated or underestimated due to coexistent confounding factors. Significant heterogeneity was also observed in the present analyses due to between-study differences. These results have important implications for decreasing the burden of AF in a variety of clinic settings through weight loss.

Authors' conclusions: “By providing a comprehensive and reliable quantification of the relationship between incremental increases in obesity and AF across different clinical settings, our findings highlight the potential for even moderate reductions in population body mass indexes to have a significant effect in mitigating the rising burden of AF.” Details, here.