Abstract 4326: High Platelet Reactivity After Clopidogrel Correlates With the Extent of Coronary Atherosclerosis and Predicts Peri-procedural Outcome in Patients With Stable Angina Undergoing Percutaneous Coronary Intervention
Background. Platelets are actively involved in vascular atherosclerosis. We tested the hypothesis that residual platelet reactivity after clopidogrel correlates with the extent and severity of coronary atherosclerosis in patients (pts) undergoing elective percutaneous coronary intervention (PCI).
Methods. We prospectively enrolled 338 pts undergoing uncomplicated PCI for stable angina, loaded with 600 mg clopidogrel. Platelet reactivity was assessed 12 hours later by measuring platelet reactivity unit (PRU) with VerifyNow P2Y12 assay. High platelet reactivity (HPR) was defined as PRU value ≥240. Presence of multi-vessel disease (MVD = stenosis >50% in at least two major coronaries) and total stent length (TSL) were used as surrogate markers of atherosclerosis severity and extension.
Results. MVD pts showed significantly higher PRU compared to single vessel disease (SVD) pts (222±85 vs. 191±73; p<0.001). PRU progressively increased with number of stenotic coronaries (1-VD: 191±73; 2-VD: 220±88; 3-VD: 226±80; p=0.002). PRU was higher in the 3rd tertile compared with the 1st tertile of TSL (217±83 vs. 191±73; p=0.015). HPR was most frequently observed among MVD pts (40.5% vs. 21.6% in SVD pts, respectively; OR 2.47, 95% CI 1.53–3.98, p<0.001) and those in the 3rd tertile of TSL (35.8% vs. 22.2% 1st tertile; OR 1.96, 95% CI 1.07–3.57, p=0.028). A higher incidence of peri-procedural myocardial infarction (MI) was observed in pts with HPR (41.2% vs. 26.7% in pts without HPR; OR 1.92, 95% CI 1.18 –3.13, p=0.008) and in those in the 3rd tertile of TSL (37.7% vs. 23.1% 1st tertile; OR 2.01, 95% CI 1.11–3.65, p=0.020). At multivariate analysis, HPR was the only independent predictor of peri-procedural MI (p=0.034).
Conclusions. Platelet reactivity after clopidogrel is significantly correlated to extent and severity of coronary atherosclerosis. HPR, more frequent in pts with MVD and higher TSL, is a strong predictor of peri-procedural MI.