Platelet Nitric Oxide Responsiveness

Abstract

Objectives— Nitric oxide (NO) is critically important in the regulation of vascular tone and the inhibition of platelet aggregation. We have shown previously that patients with acute coronary syndromes (ACS) or stable angina pectoris have impaired platelet responses to NO donors when compared with normal subjects. We tested the hypotheses that platelet hyporesponsiveness to NO is a predictor of (1) cardiovascular readmission and/or death and (2) all-cause mortality in patients with ACS (unstable angina pectoris or non–Q-wave myocardial infarction). Methods and Results— Patients (n=51) with ACS had evaluation of platelet aggregation within 24 hours of coronary care unit admission using impedance aggregometry. Patients were categorized as having “normal” (≥32% inhibition of ADP-induced aggregation with the NO donor sodium nitroprusside; 10 μmol/L; n=18) or “impaired” (P =0.041) and all-cause mortality (relative risk, 6.3; 95% CI, 1.09 to 36.7; P =0.033). Conclusions— Impaired platelet NO responsiveness is a novel, independent predictor of increased mortality and cardiovascular morbidity in patients with high-risk ACS.