Increased myocardial ischemia after food is not explained by endothelial dysfunction.

BACKGROUND

Recent studies suggest that a high-fat meal can impair endothelial function. The aim of this study was to determine whether greater myocardial ischemia after either a low-fat or a high-fat meal is associated with an increase in brachial artery endothelial dysfunction.

METHODS

Twenty subjects with coronary artery disease and > or =1-mm ST-segment depression during exercise were studied. In a randomized, double-blind, crossover design, ST-segment changes during treadmill exercise and brachial artery diameter and flow-mediated dilation were measured before and 3 hours after a low-fat milkshake meal or the same meal supplemented with 64 grams of cooked fat.

RESULTS

After the low-fat but not the high-fat meal, resting brachial artery diameter decreased (before meal 4.72 +/-0.50 mm, after low fat meal 4.62 +/-0.49 mm, P =.001; after high fat meal 4.70 +/-0.51 mm, not significant). High-flow brachial artery diameter was similar before (4.81 +/- 0.48 mm) and after the low-fat (4.82 +/- 0.48 mm) and high-fat (4.84 +/- 0.48 mm) meals (P >.05 for all). Brachial artery flow-mediated dilation was not impaired after either meal. Exercise duration decreased more after the low-fat meal (mean change 39 seconds, 95% CI -14 to -63 seconds, P =.004) than after the high-fat meal (-7 seconds, 95% CI +19 to -34 seconds, not significant). ST-segment depression during equivalent exercise was greater after compared with before both meals (before meals 1.03 +/- 0.69 mm, after low fat 1.27 +/- 0.80 mm, P =.03; after high fat 1.24 +/- 0.74 mm, P =.04).

CONCLUSIONS

Increased myocardial ischemia after food is caused by mechanisms other than endothelial dysfunction and by meal components other than cooked fat.