Circulating monocyte-platelet aggregates are an early marker of acute myocardial infarction

OBJECTIVES We investigated whether elevated levels, of circulating monocyte -platelet aggregates (MPA) can be used to identify patients with acute myoc ardial infarction (AMI). BACKGROUND Commonly used blood markers of AMI reflect myocardial cell death , but do not reflect the earlier pathophysiologic processes of plaque ruptu re, platelet activation and resultant thrombus formation. Circulating MPA f orm after platelet activation. METHODS In a single center between October 1998 and November 1999, we measu red circulating MPA in a blinded fashion by whole blood flow cytometry in 2 11 consecutive patients who presented to the emergency department (ED) with chest pain and were admitted to rule out AMI. Acute myocardial infarction was diagnosed by a CK-MB fraction greater than three times control. RESULTS Patients with AMI (n = 61), as compared with those without AMI (n = 150), had significantly higher numbers of circulating WA (11.6 +/- 11.4 vs . 6.4 +/- 3.6,mean +/- SD, p < 0.0001). After controlling for age, the adju sted odds of developing AMI for patients in the 2nd, 3rd and 4th quartiles of MPA, in comparison with patients in die lowest quartile (odds ratio = 1. 0), were 2.1 (95% confidence interval [CI]: 0.7, 6.8), 4.4 (95% CI: 1.5, 13 .1) and 10.8 (95% CI: 3.6, 32.0), respectively. The number of circulating M PA in patients with AMI presenting within 4 h of symptom onset (14.4) was s ignificantly greater than those presenting after 4 h (9.4) and after 8 h (7 .0), (p < 0.001). Of the 61 patients with AMI, 35 (57%) had a normal creati ne kinase isoenzyme ratio at the time of presentation to the ED, but had hi gh levels of circulating, NTA (13.3). CONCLUSIONS Circulating MPA are an early marker of AMI. (C) 2001 by the Ame rican College of Cardiology.