Brachial artery endothelial function predicts platelet function in control subjects and in patients with acute myocardial infarction

Platelet activation occurs in an endothelium-dependent flow-mediated dilation (FMD) impairment environment. The aim of this study was to explore the association between platelet reactivity and brachial artery FMD in individuals without established cardiovascular disease (controls) and acute myocardial infarction (AMI) patients. We prospectively assessed brachial artery FMD in 151 consecutive subjects, 104 (69%) controls, and 47 (31%) AMI patients; 115 (76%) men, mean age 53±11 years. Following overnight fasting and discontinuation of all medications for≥12h, percent change in brachial artery FMD (%FMD) and endothelium-independent, nitroglycerin-mediated vasodilation (%NTG) were assessed. Platelet aggregation was assessed by conventional aggregometry, and platelet adhesion and aggregation under flow conditions by cone-and-plate(let) technology (Impact-R). Smoking, diabetes, and hypertension were more common in AMI compared to control subjects (p<0.01 for all). Furthermore, aspirin, clopidogrel, beta-blockers, angiotensin-converting enzyme inhibitors, and statin administration were more common in AMI compared to controls (p<0.01 for all). %FMD but not %NTG was significantly lower in AMI patients compared to controls (10.2±4.2% vs. 15.4±4.4%; p<0.001 and 17.2±3.9% vs. 18.0±3.7%, p=0.803, respectively). %FMD was significantly and inversely associated with all platelet functions tests (p<0.001) in all study participants. In a multivariate logistic regression (unadjusted and adjusted for age, gender, smoking status, diabetes mellitus, hypertension, hypercholesterolemia, overweight, family history, and concomitant medications), %FMD remained the best predictor of platelet function, irrespective of group allocation (AMI patients or controls). In conclusion, FMD is inversely correlated to platelet reactivity in both controls and AMI patients.