Intrinsic platelet reactivity and thrombus burden in patients with ST-elevation myocardial infarction.

INTRODUCTION

In patients with ST elevation myocardial infarction (STEMI) increased platelet reactivity has been described to affect the primary percutanuous coronary intervention (PPCI) outcome. We aimed to evaluate the predictive accuracy of intrinsic platelet reactivity for intracoronary thrombus burden in P2Y12 inhibitor- naïve STEMI patients.

PATIENTS AND METHODS

In a prospective, observational, cohort study we enrolled 94 consecutive STEMI patients undergoing PPCI, subjected to platelet reactivity assessment prior to any P2Y12 blockade, with visible angiographic thrombus in the infarct related artery (stratified as Grade A, B and C). Platelet-function testing was performed with the VerifyNow point-of-care P2Y12 assay immediately prior to intervention.

RESULTS

Intrinsic platelet reactivity was higher with greater thrombus burden: Grade A 158.8±51.1 PRU, Grade B 217.4±62.1 PRU and Grade C 243.4±58.6 PRU, p=0.009 and Spearman r=0.32 (0.12-0.49 95% CI), p=0.002. ROC analysis revealed an AUC=0.7 (Standard error 0.07, p=0.03). An intrinsic platelet reactivity value of >220 PRU had 65% sensitivity (53-76 95%CI), 76% specificity (55-91 95%CI), 88% positive predictive value (76-96 95%CI) and 44% negative predictive value (29-60 95%CI) for detection of high thrombus burden. In multivariate analysis intrinsic platelet reactivity >220 PRU emerged as an independent predictor of high thrombus burden (RR=1.5, 1.15-2.07 95% CI, p=0.004).

CONCLUSIONS

In patients admitted with STEMI the intrinsic platelet reactivity -as assessed by a point-of-care assay- is positively associated with the degree of intracoronary thrombus, while having a moderate accuracy in predicting high thrombus burden.