NEW YORK (Reuters Health) – In patients with atrial fibrillation, a body mass index (BMI) of 27.0 kg/meters-squared or higher increases the risk for left atrial/left atrial appendage (LA/LAA) thrombi, according to a report in the December 15th American Journal of Cardiology.
Obesity is associated with poor prognosis in patients with atrial fibrillation, the authors point out, with some studies suggesting that obese patients with atrial fibrillation could face a high risk of thromboembolic complications.
Dr. Ri-Bo Tang from Capital Medical University, Beijing, China and colleagues investigated 433 patients admitted for catheter ablation of nonvalvular atrial fibrillation and found, first, that higher BMI does increase the risk for thrombi, and second, that the 27.0 kg/meters-squared threshold “stands as a clear limit above which the risk of LA/LAA thrombus in patients with atrial fibrillation is substantial.”
Overall, LA/LAA thrombus was detected in 26 patients (6.0%) by transesophageal echocardiography, the authors report.
These patients had a significantly higher mean BMI (27.9 kg/meters-squared) compared to patients without LA/LAA thrombus (26.0 kg/meters-squared). There was no significant difference in the prevalence of overweight and obesity between patients with and without thrombus.
The incidence of LA/LAA thrombus was 10.6% in patients with BMI of 27.0 kg/meters-squared or greater, versus 3% in patients with lower BMI.
On multivariate analysis, independent risk factors for LA/LAA thrombus were a BMI of at least 27.0 kg/meters-squared (odds ratio, 4.02), a CHADS2 score (Cardiac failure, Hypertension, Age, Diabetes, Stroke Doubled) of at least 2 (OR, 5.06), and nonparoxysmal atrial fibrillation (OR, 4.06).
“The exact mechanism linking obesity to a higher risk of LA/LAA thrombus remains to be investigated,” the authors conclude.
Also unclear, they add, is the applicability of their findings when the threshold for obesity is defined as a BMI of 30 kg/meters-squared.
Reference:
Am J Cardiol 2009;104:1699-1703.
