BACKGROUND: In vitro “high post-clopidogrel platelet reactivity” (HPPR) measured with ADP-induced light transmittance aggregometry (LTA) and VerifyNow P2Y12 assay (VN-P2Y12) has been associated with an increased risk of thrombotic complications after percutaneous coronary intervention. However, there are many criteria of HPPR according to used methods and time, and correlations between suggested criteria of HPPR are not determined.
METHODS: We performed LTA (both 5 and 20 umol/l ADP-induced) and VN-P2Y12 simultaneously in unselected patients on clopidogrel. During the study period, 1,058 patients with coronary stenting were enrolled. Based on previous studies, 5 or 20 umol/l ADP-induced maximal platelet reactivity (PRmax) ≥ 50%, 5 umol/l ADP-induced late PR (PRlate) > 14% and P2Y12 reaction unit (PRU) ≥ 240 were accepted as the criteria of HPPR.
RESULTS: Receiver-operating characteristics (ROC) curve analysis of VN-P2Y12 demonstrated that PRU (cut-off = 241) could distinguish between patients with and without 5 umol/l ADP-induced PRmax ≥ 50% (area under curve [AUC] 0.822, 95% CI 0.797 to 0.847, p < 0.001), providing a sensitivity of 83.0% and a specificity of 66.0%. PRU ≥ 240 showed a significant, moderate agreement with 5 ųmol/l ADP-induced PRmax ≥ 50% (κ = 0.438, 95% CI 0.371 to 0.465, p < 0.001), with a concordant rate of 71.4%. The AUC of PRU for 20 ųmol/l ADP-induced PRmax ≥ 50% was 0.851 (95% CI 0.827 to 0.875, p < 0.001), and a PRU ≥ 195 showed a sensitivity of 88.9% and a specificity of 63.2%. In terms of 5 ųmol/l ADP-induced PRlate > 14, AUC of PRU was 0.826 (95% CI 0.796 to 0.856, p < 0.001), and a PRU ≥ 194 showed a sensitivity of 82.9% and a specificity of 68.3%. Cut-off PRU between 20 ųmol/l ADP-induced PRmax ≥ 50% and 5 ųmol/l ADP-induced PRlate > 14 was very similar, and a significant marked agreement was present between the criteria (concordant rate 83.9%, κ = 0.602, 95% CI 0.381 to 0.488, p < 0.001),.
CONCLUSONS: There are significant correlations between the criteria of HPPR based on clinical studies. Point-of-care VN-P2Y12 may be used for assessing the cut-off of HPPR, which has a practical implication for high-risk stratification of ischemic events.
|
