OBJECTIVES: We tested the hypothesis that residual platelet reactivity after clopidogrel correlates with the extent and severity of coronary atherosclerosis in patients undergoing elective percutaneous coronary intervention (PCI).
BACKGROUND: Platelets are actively involved in vascular atherosclerosis.
METHODS: We prospectively enrolled 338 patients undergoing PCI for stable angina, loaded with 600-mg clopidogrel. Platelet reactivity was assessed 12 h later by measuring P2Y12 reactivity unit (PRU) with VerifyNow P2Y12 assay (Accumetrics, San Diego, California). High platelet reactivity (HPR) was defined as PRU value >or=240. Presence of multivessel disease (MVD) and total stent length (TSL) were used as surrogate markers of atherosclerosis severity and extension.
RESULTS: Patients with MVD showed higher PRU compared with single-vessel disease (SVD) patients (222 +/- 85 vs. 191 +/- 73; p < 0.001). The PRU increased with the number of stenotic coronaries (1-vessel disease: 191 +/- 73; 2-vessel disease: 220 +/- 88; 3-vessel disease: 226 +/- 80; p = 0.002). The PRU was higher in the third TSL tertile compared with first tertile (217 +/- 83 vs. 191 +/- 73; p = 0.048). The HPR was most frequently observed among MVD patients (40.5% vs. 21.6% in patients with SVD, respectively; p < 0.001) and those in the third TSL tertile (35.8% vs. 22.2% first tertile; p = 0.028). Higher incidence of periprocedural myocardial infarction was observed in patients with HPR (41.2% vs. 26.7% in patients without HPR; p = 0.008) and in those in the third tertile TSL (37.7% vs. 23.1% first tertile; p = 0.020). By multivariate analysis, HPR was the only independent predictor of periprocedural myocardial infarction (p = 0.034).
CONCLUSIONS: Patients with more extensive coronary atherosclerosis have a higher rate of HPR, which might partly account for higher risk of periprocedural MI.