News:Study on the Effect of Obesity on Mortality Rates Following MI

July 3rd, 2007 By Scott P. Williams [mailto:swilliams@perfuse.org]

The study consisted of 1676 unselected consecutive patients who demonstrated myocardial ischaemia at rest without persistent ST-segment elevation. Using the body mass index (BMI) standards put forth by the World Health Organization, approximately 50% of the 1676 patients enrolled in the study were classified as overweight, and an additional 18% were classified as obese or very obese. Patients with persistent chest pain underwent immediate angiography and, when possible, stenting of the culprit lesion. Following their procedure patients received a six month follow up and were requested to complete regular questionnaires.

During the study's approximately three year follow up period obese and very obese patients demonstrated a greater survival rate following MI than patients classified as having a normal BMI. The research suggests "a linear  association between BMI and mortality in patients with UA/NSTEMI receiving contemporary treatment." The research team primarily asserts that obese patients are more likely to have cardiovascular disease diagnosed and treated prior to suffering MI than are patients with a normal BMI. Secondary reasons suggested included: "endogenous cannabinoids, lower platelet count, excess triglyceride content in heart tissue including areas of healed MI, and lower age." 

The study included a limited number of patients with severe obesity (BMI of 40 or greater), and the results should not be further extrapolated to include this group. The authors note that BMI does not directly reflect body fat content. They suggest that further studies utilizing more targeted measures of obesity should yield more refined results. Additionally, they observe that obesity is an important risk factor in developing cardiovascular disease in the first place. Obese patients are more likely to survive a heart attack, but they are also more likely to have a heart attack. The study concludes that patients classified as obese and very obese according to BMI demonstrated less than half the mortality when compared to patients with normal BMI.


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