Obesity Linked to Lower Stroke and Mortality Risk in Elderly AF Patients on Anticoagulants

Obesity Linked to Lower Stroke and Mortality Risk in Elderly AF Patients on Anticoagulants

A team of researchers reported that obesity was associated with a lower stroke and mortality rate in elderly atrial fibrillation patients treated with anticoagulants. Moreover, obesity was related to good quality anticoagulation. The study, published in the journal Stroke, is entitled “Body Mass Index and Adverse Outcomes in Elderly Patients With Atrial Fibrillation The AMADEUS Trial.

Evidence has shown that obesity is associated with increased cardiovascular risk in atrial fibrillation (AF). Despite these data, little is known about the effect of obesity on adverse outcomes in elderly patients with AF on oral anticoagulants, such as warfarin or acenocoumarol.

To address this gap, Keitaro Senoo, MD, and Gregory Y.H. Lip, MD, both of the University of Birmingham Institute of Cardiovascular Sciences, City Hospital, in the United Kingdom, analyzed data from the AMADEUS (Evaluating the Use of SR34006 Compared to Warfarin or Acenocoumarol in Patients With Atrial Fibrillation) clinical trial.

The purpose of the trial was to compare the safety and effectiveness of a new injectable anticoagulant drug administered once per week, SR34006, with warfarin or acenocoumarol tablets. Patients were randomly assigned to either SR34006 injection or vitamin K antagonists (warfarin or acenocoumarol).

The trial included patients with atrial fibrillation, an abnormal rhythm (irregular beat) in the heart. Patients with atrial fibrillation have an increased chance for a blood clot to form in the heart and move to obstruct blood vessels elsewhere in the body, possibly damaging tissue. Because a blood clot plugging a vessel in the brain could cause a stroke, atrial fibrillation patients may be given anticoagulant (blood-thinning) tablets.

A total of 1,588 elderly patients, ages 75 or older, were included in the pos-hoc analysis. Of the total, 515 patients were categorized as having normal body mass index (BMI, 18.5–25 kg/m2), 711 patients as being overweight (BMI, 25–30 kg/m2), and 362 patients as being obese (BMI≥30 kg/m2).

The results revealed that there was a significant reduction in the primary outcome of composite cardiovascular death and stroke/systemic embolism with increasing BMI category, being 5.0%, 3.2%, and 1.5% per 100 patient-years, respectively.

Further multivariate statistical analysis showed that obesity was associated with a lower risk of the primary composite outcome. In the warfarin arm (n=814), results revealed that obesity was independently related to a trend toward improved time to therapeutic range (52% in normal weight patients, 57% in overweight, and 60% in obese).

In the entire cohort, the results showed a lower risk for CV death, stroke and stroke/systemic embolism among patients with obesity versus the reference of normal BMI. Although a similar trend was seen in patients on warfarin, the findings were not significant.

The researchers cited possible explanations for the association between obesity and improved stroke and mortality outcomes, including the use of more cardiovascular death prevention strategies, greater metabolic reserve, and lower natriuretic peptide levels.

“Given the close relationship between [time in therapeutic range] and outcomes, obesity in elderly patients with AF might be linked with less adverse outcomes when compared with normal-weight patients,” the researchers wrote, according to a recent news release. “As we are limited in power to fully explore the association between [time in therapeutic range] and individual adverse outcomes in warfarin arm because of the low event rates, further studies are needed to explore this hypothesis.”

“Obesity is associated with lower risk of combined CV death and stroke/systemic embolism in elderly AF patients on anticoagulation. Obesity is associated with the good quality of warfarin control (better TTRs), which may have a positive impact on adverse outcomes,” the researchers concluded.

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