Abstract 18272: Impact of Body Mass Index and Gender on Left Atrial Size and the Presence of Atrial Fibrillation

Abstract

Background: Atrial fibrillation (AF) is frequently observed in overweight and obese adults. There is limited data on whether increased body mass index (BMI) is independently associated with left atrial (LA) enlargement or the presence of AF. We sought to evaluate the impact of BMI on LA size and presence of AF and to assess whether it is gender specific. Methods: We reviewed 1,200 consecutive transthoracic echocardiograms performed at a tertiary care medical center. A total of 701 tests were excluded due to significant mitral valve disease or incomplete LA assessment. LA measurements obtained included A-P diameter from parasternal long axis view, LA area (LAA) and volume (LAV) from apical 2- and 4-chamber views and indexed LA volume to body surface area (LAVI). Patients were divided into three groups according to BMI: normal BMI between 18.5 and 24.9, overweight with a BMI between 25 and 30 and obese with a BMI greater than 30. Results: Among 499 patients included in this analysis, 259 (51.9%) were female and 240 (48.1%) were male. Of these, 151 (30.1%) had normal BMI, 181 (36.3%) were overweight and 167 (33.5%) were obese. Obese patients were younger, hypertensive, diabetic, and had larger LA diameter, LAA, and LAV, but similar LAVI. Using multivariate analysis, BMI and gender were both found to be independently associated with LA diameter (p<0.001 for both) and LAA (p<0.001 for both) but not LAVI or the presence of AF. Predictors of LA diameter in men and women included age, BMI, and right ventricular systolic pressure (RVSP). Left ventricular ejection fraction (LVEF) was an independent predictor of LA diameter and LAA in women but not men. Predictors of AF included LAVI (OR 1.046, 95%CI 1.023-1.070) in men and LAA (OR 1.227, 95%CI 1.130-1.333) and age (per year) (OR 1.041, 95%CI 1.008-1.075) in women. Conclusions: BMI and gender are independent predictors of LA diameter and LAA but not of LAVI or AF. However, LAVI is an independent predictor of AF in men, whereas LAA and age are independent predictors of AF in women.