Abstract 2042: Does Aspirin Have a Positive Influence on Coronary Endothelial Function?-Importance of The Dose-
Background: It is well known that aspirin prevents coronary events in patients with or without previous coronary artery disease thanks to its anti-platelet effect. However, it remains unclear whether its preventive effect is due to an improvement of coronary endothelial function. Furthermore, if aspirin improved coronary endothelial function, it would be necessary to investigate the dose required to attain such effect. We investigated the effect of aspirin on coronary endothelial function at different doses.
Methods: The subjects were 135 Japanese (mean age: 60 years; 50 women) with angiographically normal coronary arteries. Patients were distributed into a Group I (n = 61) administered aspirin, and a Group II (n = 75) that served as the control. Furthermore, subjects in Group I were distributed into Group Ia (n = 48) given a low dose (100 mg) and Group Ib (n = 13) given a high dose (500 mg) of aspirin. After routine coronary angiography, acetylcholine (ACh, 3 and 30 μg/min) and nitroglycerin (NTG) were infused into the left coronary ostium over 2 min. The change in coronary artery diameter in response to each drug was expressed as the percent change from the baseline values.
Results: The characteristics of the patients did not differ between the 2 groups; hemodynamics and coronary artery diameter at baseline were similar. The change in coronary diameter in response to ACh was greater in Group I (3 μg/min: 1.8±0.9% vs. 0.1±0.8 %, 30 μg/min: 1.1±1.1% vs. −3.9±1.0%, p = 0.0051). On the other hand, NTG-induced coronary vasodilation was similar in the 2 groups (Group I: 14.1±1.5%, Group II: 15.6±1.4%). ACh-induced dilation was greater in Group Ia (3 μg/min: 2.3±1.0% vs. −0.4±2.0%, 30 μg/min: 2.4± 1.3% vs. −3.9±2.4%, p<0.05). Multivariate regression analysis showed that a low dose of aspirin (p = 0.0011, t value = 3.35) and nitroglycerin (p = 0.0007, t value = 3.48) were associated with the percent change in coronary diameter in response to ACh at a dose of 30 μg/min.
Conclusions: In subjects with angiographically normal coronary arteries, aspirin had a positive influence on coronary endothelial function only at the low dose of 100 mg. This improvement of coronary endothelial function may be involved in the preventive effect of aspirin regarding future coronary events.