Aside from aging itself, obesity appears to be the most powerful predictor of left atrial enlargement (LAE), upping one's risk of atrial fibrillation (the most common type of arrhythmia), stroke and death, according to findings published in the November 17, 2009, issue of the Journal of the American College of Cardiology.

The left atrium is the chamber of the heart that receives oxygenated blood from the lungs. The heart pumps blood from the left atrium, through the mitral valve, into the left ventricle and out to the body. Any condition that increases pressure in this portion of the system can lead to enlargement of the left atrium. These conditions may include hypertension, valve problems, heart failure or atrial fibrillation.