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Special groups: body mass index

Analysis of the ENGAGE AF –TIMI study has shown that obese patients with atrial fibrillation (AF) had a lower risk of stroke/systemic embolic events (SEE) and better survival than AF patients with a normal body mass index (BMI), but the risk of bleeding was higher in patients with a BMI ≥ 25.1

In the study, patients with atrial fibrillation and a CHA2DS2-VASc score ≥ 2, were randomised to warfarin or edoxaban (higher or lower dose).  There were available data for BMI (kg/m2) for 21,028 patients, with 0.8% being underweight (BMI <18.5); 21% normal (BMI 18.5–25); 38% overweight (BMI 25–30); 25% moderately obese (BMI 30–35); 10% severely obese (BMI 35–40); and 5% very severely obese (BMI >40).

The subanalysis looked if there was any difference in outcomes in these patients. The primary end point was stroke/SEE, and the principal safety end point was major bleeding.

Results showed that patients with higher BMIs were more likely female, enrolled in North America, and to have diabetes, heart failure and hypertension requiring treatment. Prior stroke or transient ischemic attack was less common as compared to patients with normal BMI. In an adjusted analysis including all patients enrolled regardless of treatment group, higher BMIs (especially if >35) were associated with a significantly lower risk of stroke/SEE and mortality compared to patients with normal BMI. Conversely there was a significantly increased risk of major bleeding with increasing BMI, even after controlling for treatment groups and other covariates. Net outcomes were similar in obese patients compared to those with normal BMI.

Similar results were also seen in analysis of the EORP-AF (Eurobservational Research Programme on Atrial Fibrillation) Pilot Registry, which looked at outcomes at one-year follow-up of AF patients, according to BMI (kg/m2), focusing on patients with normal BMI (defined as 18.5 to <25kg/m2), overweight (25 to <30kg/m2) and obesity (≥30kg/m2).

Women with an increased BMI were found to have lower all-cause mortality and stroke, in line with the so called “obesity paradox”. In male patients, obesity was associated with more bleeding. Obese patients were also younger and with higher prevalence of diabetes and hypertension (p<0.0001).2


1. Boriani G et al. Relationships between body mass index and outcomes in 21,098 patients with atrial fibrillation and treated with edoxaban or warfarin in ENGAGE AF-TIMI 48 trial. Abstract P5875. Eur Heart J 2016;37(Abstract supplement):1199.

2. Boriani G et al. Overweight and obesity in female and male patients with atrial fibrillation: insights from the EURObservational Research Programme on Atrial Fibrillation (EORP-AF) Pilot Registry. Abstract P4621. Eur Heart J 2016; 37(Abstract Supplement): 929.

Published on: October 19, 2016

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  • ArrhythmiaAlliance
  • Stars
  • Anticoagulation Europe
  • Atrial Fibrillation Association

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