Doctors have suspected for a long time that overweight patients appear to have an increased risk of developing heart failure, but most believed that the heart failure resulted from the diabetes, high blood pressure and coronary artery disease associated with obesity. Now, however, a new study - published in the August 1 issue of the New England Journal of Medicine - shows that obesity itself (and not just the associated medical conditions) can lead to heart failure.
Furthermore, the study shows that even excess body weight - in people who are not considered obese - substantially increases the risk of heart failure.
The investigators followed 5881 individuals enrolled in the Framingham Heart Study, who were either obese or merely overweight, for an average of 14 years. After adjusting statistically for other risk factors for heart failure (such as diabetes, coronary artery disease or hypertension,) those who were merely overweight had a risk of developing heart failure that was 34% greater than in non-overweight individuals; while those who were obese had an incredible 104% increase in risk.
The bottom line: even if you're entirely healthy otherwise, being obese (or merely overweight) still places you at risk of developing heart failure. This new finding should give both doctors and patients even more impetus to encourage weight loss (as if they didn't have enough already.)
Why does obesity lead to heart failure?As pointed out in an editorial that accompanies this article, there are problems associated with obesity that were not accounted for by this study. It is known that obesity can cause left ventricular hypertrophy (LVH, or thickening of the wall of the heart's left ventricle,) for instance. Longstanding LVH can eventually lead to heart failure. Further, obesity is associated with metabolic syndrome X - a metabolic disorder that can cause serious lipid abnormalities. It is possible that the LVH and/or metabolic syndrome (neither of which were accounted for in this study) may explain some or all of the excess in heart failure observed in overweight patients.
If so, then treatments aimed at ameliorating the LVH and metabolic syndrome X might help to prevent heart failure. This theory will undoubtedly be tested in clinical trials. Until then, prudence dictates that individuals who are substantially overweight redouble their efforts to exercise and lose weight. If they have hypertension, lipid abnormalities, metabolic syndrome X, or other risk factors for heart disease, aggressive management of all risk factors is needed.