Platelet nitric oxide responsiveness: a novel prognostic marker in acute coronary syndromes.
OBJECTIVE
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).


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" (> or =32% inhibition of ADP-induced aggregation with the NO donor sodium nitroprusside; 10 micromol/L; n=18) or "impaired" (<32% inhibition of ADP-induced aggregation; n=33) NO responses. We then compared the incidence of cardiovascular readmission and death during a median of 7 years of follow-up in these 2 groups. Using a Cox proportional hazards model adjusting for age, sex, index event, postdischarge medical treatment, revascularization status, left ventricular systolic dysfunction, concurrent disease states, and cardiac risk factors, impaired NO responsiveness was associated with an increased risk of the combination of cardiovascular readmission and/or death (relative risk, 2.7; 95% CI, 1.03 to 7.10; 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.
Willoughby
Scott R
SR
Basil Hetzel Institute, Queen Elizabeth Hospital, Department of Medicine, University of Adelaide, Adelaide, Australia.
Stewart
Simon
S
Holmes
Andrew S
AS
Chirkov
Yuliy Y
YY
Horowitz
John D
JD
D000208:Acute Disease; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers; D001792:Blood Platelets / Q000378:metabolism*; D002423:Cause of Death; D003328:Coronary Thrombosis / Q000378:metabolism* / Q000401:mortality*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009017:Morbidity; D015999:Multivariate Analysis; D017202:Myocardial Ischemia / Q000378:metabolism / Q000401:mortality; D009569:Nitric Oxide / Q000378:metabolism*; D010974:Platelet Aggregation; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D012307:Risk Factors
D015415:Biomarkers; D009569:Nitric Oxide