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 ≥ 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% Cl −14 to −63 seconds, P = .004) than after the high-fat meal (−7 seconds, 95% Cl + 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.