Obesity and the prognosis of heart failure: the obesity paradox, myth or reality?

Obesity has now reached epidemic proportions worldwide. Obesity is associated with numerous comorbidities, including hypertension, lipid disorders and type II diabetes, and is also a major cause of cardiovascular disease, coronary disease, heart failure, atrial fibrillation, and sudden death. Obesity is the main cause of heart failure in respectively 11 % and 14 % of cases in men and women. The Framingham study showed that, after correction for other risk factors, each point increase in the body mass index raises the risk of heart failure by 5 % in men and 7 % in women. Obesity increases the heart workload, causes left ventricular hypertrophy, and impairs both diastolic and systolic function. The most common form of heart failure is diastolic dysfunction, and heart failure in obese individuals is associated with preserved systolic function. Despite these comorbidities and the severity of heart failure, numerous studies have revealed an "obesity paradox" in which overweight and obese individuals with heart failure appear to have a better prognosis than non overweight subjects. This review summaries the adverse cardiac effects of this nutritional disease, the results of some studies supporting the obesity paradox, the better survival rate of obese patients with heart failure. Potential explanations for these surprising data include the possibility that a number of obese patients may simply not have heart failure, as well as methodological bias, and protective effects of adipose tissue. Further studies of large populations are needed to determine how obesity may improve the prognosis of heart failure.