Metabolically healthy and unhealthy obesity increase atrial fibrillation (AF) risk at a similar rate, according to research findings published in Obesity.
Some previous research has indicated differences in cardiovascular risk between healthy and unhealthy obesity phenotypes. However, these studies had conflicting results and did not consider duration or severity of obesity in a large population. To evaluate the effects of “metabolically healthy obesity” on risk for AF using validated AF diagnoses, researchers conducted a population-based study using data from the third Nord-Trøndelag Health study.
Adults age ≥20 years in Norway were classified according to body mass index (BMI) and metabolic status and monitored from 2006 to 2008. Definitions for metabolic status were based on the International Diabetes Federation standards and were modified slightly. Data for AF diagnoses were obtained through discharge registers from baseline through 2015. The researchers used Cox proportional regression models to assess risk for AF in groups with different classes of BMI and metabolic status.
Of 47,870 patients, 10,775 (22.5%) were obese and 19,332 (40.4%) were metabolically unhealthy. Among obese patients, 27.4% were metabolically healthy. After a median follow-up of 8.1 years, AF developed in 1758 (3.7%) participants. Compared with healthy normal-weight individuals, multivariable-adjusted hazard ratios for metabolically healthy vs unhealthy obesity were 1.6 (95% CI, 1.2-2.1) vs 1.6 (95% CI, 1.3-1.9), respectively. When BMI was subdivided into 4 categories, risk for AF was not consistently higher for metabolically unhealthy participants vs metabolically healthy participants for each BMI category. AF risk was positively correlated with severity of obesity.
Overall, the study indicated that there is no such thing as “healthy” obesity with regard to AF risk. “However, among [patients] who had only recently [become] overweight or obese, only metabolically unhealthy participants had higher AF risk. This may suggest that metabolically healthy overweight/obesity represents an initially benign condition but exacts a greater toll with continued duration,” stated the researchers.
Feng T, Vegard M, Strand LB, et al. Metabolically healthy obesity and risk for atrial fibrillation: the HUNT study [published online January 3, 2019]. Obesity (Silver Spring). doi: 10.1002/oby.22377