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In people with coronary artery disease, is fat a friend or foe? (RCT, CHEST)
One thing I thought I knew was that overweight and obesity cause coronary artery disease and make it worse. People with CAD who are obese should lose weight ... right?
Recent research shows it's not that simple (although the answer is still "yes, probably").
Did you know about the "obesity paradox?" Or the "lean paradox," if you like? (I didn't.) In study after review after meta-analysis, people with coronary artery disease who are obese have a better prognosis than lean people with CAD. Huhwhat? Yes. It's vexing enough that the great CHF expert Greg Fonarow has argued that until randomized trials are done, maybe obese patients with CAD shouldn't lose that extra weight, in case it's protective somehow.
But ... what about all that hubbub about metabolic syndrome increasing CAD risk, with its defining characteristic of central-obesity adipose as an endocrine organ secreting noxious, atherogenic pro-inflammatory mediators ... all that stuff? With all the benefits of exercise and weight loss, surely losing the spare tire would help, expert hand-wringing notwithstanding?
Philip Ades et al enrolled 38 overweight patients with known coronary artery disease to walk for either 45-60 minutes 1-3 times per week, or 24-40 minutes per session in a 4-month supervised exercise program.
The high-intensity exercise group lost more weight (8.6 kg vs. 2.3 kg), waist circumference, and had greater improvements in metabolic parameters (lipids, insulin sensitivity).
These long-walkers also had a greater improvement in their flow-mediated dilation of the brachial artery, a validated predictor of cardiovascular events, than the lighter-exercisers.
There was a dose response relationship: the more weight that was lost, the greater the improvement in brachial artery responsiveness.
Authors point out that weight loss is not currently a focus of cardiac rehabilitation programs, and that in fact their outcomes (in terms of weight loss) are "abysmal." They make the case that weight loss needs to become a pillar of such programs.
As to that obesity paradox? In an editorial, Lavie and Milani hypothesize that the solution is as follows: obese people get CAD in part or in whole because of their obesity, but lean people get CAD for other (genetic) reasons, and this distinct "lean" form of CAD tends to be a more lethal disease.
Ades PA et al. The Effect of Weight Loss and Exercise Training on Flow-Mediated Dilatation in Coronary Heart Disease. A Randomized Trial. CHEST 2011;140:1420-1427.
EDITORIAL: Lavie CJ, Milani MV. Weight Reduction and Improvements in Endothelial Function. Combating the “Obesity Paradox” in Coronary Heart Disease. CHEST 2011;140:1395-1396.