Validation of Three Platelet Function Tests for Bleeding Risk Stratification During Dual Antiplatelet Therapy Following Coronary Interventions

Background: Although low platelet reactivity (LPR) is commonly detected during bleeding, a validated threshold for reliable DAPT bleeding risk stratification is lacking. We tested the diagnostic utility of 3 conventional platelet-activity assays to define the predictive value (if any) of LPR for bleeding. Hypothesis: We hypothesized whether one of these tests be better than any others for predicting bleeding events. Methods: Patients (n = 800) following drug-eluting stent implantation received DAPT. Bleeding was assessed by Bleeding Academic Research Consortium (BARC) classification and events were collected for 1 year after stenting. Platelet reactivity was measured by light transmittance aggregometry (LTA), VerifyNow, and multiple electrode aggregometry (MEA). The LPR values for bleeding event stratification were defined as ≤15% for LTA, ≤139 PRU for VerifyNow, and ≤25 U for MEA. Results: Bleeding events occurred in 18 patients (2.3%). All tests distinguished LPR as an independent predictor for bleeding by univariate analysis ([HR]: 5.00, 95% [CI]: 1.8-14.0, P = 0.002 for LTA; HR: 21.3, 95% CI: 6.2-73.0, P <0.0001 for VerifyNow; and HR: 7.4, 95% CI: 2.2-25.5, P = 0.002 for MEA). Multivariate analysis revealed that only VerifyNow (HR: 11.5, 95% CI: 2.9-45.7, P <0.0004) remained an independent predictor for bleeding. However, the specificity (81.5%, 60.2%, and 81.7%, respectively) and sensitivity (61.1%, 83.3%, and 83.2%, respectively) of all 3 tests were quite low. Conclusions: Among 3 conventional platelet-activity assays, VerifyNow was better than LTA or MEA for triaging future bleeding risks. However, all 3 tests failed to reliably predict future bleeding.