Obesity Paradox Reported in Atrial Fibrillation Outcomes

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All-cause mortality and cardiovascular death outcomes may be paradoxically improved in obese patients with atrial fibrillation.
All-cause mortality and cardiovascular death outcomes may be paradoxically improved in obese patients with atrial fibrillation.

Data from a study published in Stroke suggest that an obesity paradox may occur in patients with atrial fibrillation (AF), particularly with regard to all-cause and cardiovascular mortality.

For the study, researchers performed a systematic review on the connection between body mass index (BMI) and major adverse events in patients with AF, and conducted a meta-analysis of non-vitamin K antagonist oral anticoagulant (NOAC) trials.

The final analysis included 5 subgroup analyses of randomized controlled trials and 8 observational studies.

 

Results revealed the presence of the obesity paradox in rates of death and all-cause mortality in subgroup analyses of randomized trial cohorts, but not in observational studies.

In the meta-analysis of NOAC trials, the risk for stroke/systemic embolic event was lower in both overweight (odds ratio [OR], 0.75; 95% CI, 0.66-0.84) and obese (OR, 0.62; 95% CI, 0.54-0.70) patients compared with normal weight patients; however, only obese patients experienced a lower risk for major bleeding (OR, 0.84; 95% CI, 0.72-0.98).

Furthermore, in normal weight patients, NOACs reduced the odds for stroke/systemic embolic event (OR, 0.66; 95% CI, 0.56-0.78) and major bleeding (OR, 0.72; 95% CI, 0.54-0.95) compared with warfarin. In overweight patients, NOACs decreased the risk for major bleeding (OR, 0.84; 95% CI, 0.71-1.00).

“There may be an obesity paradox in AF patients, particularly for all-cause and cardiovascular death outcomes,” the researchers concluded.

“Despite this, data from observational studies show that after full adjustments for baseline characteristics, an obesity paradox is no longer evident, highlighting the role of comorbidities and risk factor management in influencing the obesity paradox and thus leaving this question still partially unanswered. However, an obesity paradox was evident for stroke/[systemic embolic event] outcome in NOAC trials, with a treatment effect significantly favoring NOACs over warfarin in normal weight patients.”

The researchers added that the conclusions do not support the maintenance of a higher BMI in patients with AF, but rather emphasize the need for a holistic approach to AF management.

“Further evidence from large prospective studies may further clarify this relationship,” the researchers wrote.

Disclosures: Two researchers report multiple financial disclosures with pharmaceutical companies. The other researchers report no relevant financial disclosures.  

Reference

Proiette M, Guiducci E, Cheli P, Lip GYH. Is there an obesity paradox for outcomes in atrial fibrillation? A systematic review and meta-analysis of non-vitamin K antagonist oral anticoagulant trials [published online March 6, 2017]. Stroke. doi:10.1161/strokeaha.116.015984

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