Associations of fat and muscle mass indices with incident atrial fibrillation: data of PREVEND

Abstract Background Whether the association between body mass and atrial fibrillation (AF) risk is driven by fat mass or muscle mass remains unclear. Objective To examine the association of relative fat mass (RFM, a novel marker of whole-body fat percentage) and 24-hour urinary creatinine excretion (a marker of total muscle mass) with incident AF. Participants: We included 8120 community-dwelling adults from the PREVEND cohort without prevalent AF. Results The mean age of the population was 49.8±12.6 years and 50.0% (n=4060) were women. The mean RFM was 30.2±7.4 % and the mean creatinine excretion was 12.3±3.5 mmol/24h. During a mean follow-up period of 9.7±2.4 years, 261 AF events (3.2%) occurred. We included RFM, creatinine excretion, age, sex, height, heart rate, hypertension and cardiovascular disease history in a multivariable Cox regression model. The association between RFM and AF risk was linear, and the hazard ratio per 1 SD increase in RFM was 1.40; 95%CI: 1.17-1.66 (P<0.001). The association between creatinine excretion and AF risk was non-linear (P-value quadratic trend=0.006): compared with individuals in tertile 2 of creatinine excretion, those in tertile 1 had a HR of 1.70; 95%CI: 1.21-2.29 (P=0.002) and those in tertile 3 also had a HR of 1.74; 95%CI: 1.22-2.47 (P=0.002). Conclusion In the general population, both fat mass and muscle mass are associated with incident AF. While obesity should be considered as a major risk factor for AF, increased AF risk in individuals with low and high muscle mass warrants further investigation.