Clinical implications of very low on-treatment platelet reactivity in patients treated with thienopyridine: the POBA study (Predictor Of Bleedings with Antiplatelet drugs)

Background: New P2Y12 blockers and platelet monitoring has been proposed to optimize platelet inhibition after Acute Coronary Syndrome (ACS) and improve ischemic outcomes. However, bleeding complications remain the "Achilles' heel" of antiplatelet therapy and platelet monitoring could be useful to evaluate this risk. Objective: The present study was designed to define the "hyper response" to thienopyridine (Very Low on-Treatment Platelet Reactivity (VLTPR)) as the most predictive threshold value of Platelet Reactivity Index VASP (PRI VASP) for prediction of non access-site related bleeding events. We also aimed to identify predictors of bleeding and VLTPR in patients treated with thienopyridines. Methods and results: 1542 consecutive patients undergoing coronary stenting for ACS were included in the present study (287 on clopidogrel 75 mg, 868 on clopidogrel 150 mg and 387 on prasugrel 10 mg). During 6-month follow-up, 9% of patients (n=139) suffered from non-access site related BARC bleeding complications. These patients were more often women, non-diabetic and had lower PRI VASP values than others (p<0.001). ROC curves analysis (AUC=0.71, p<0.01) identified a threshold value for VLTPR of PRI VASP≤10% to predict bleeding events with a sensitivity of 17% and a specificity of 97%. While prasugrel was the main predictor of VLTPR in the whole population (OR [95% CI]: 10.2 [3–34.2]; p<0.001), VLTPR was the strongest and independent predictor of bleeding (OR [95% CI]: 4.7 [2.7–8.3]; p<0.001). ![Figure][1] Figure 1. Impact of VLTPR on bleedings Conclusion: The present study identified VLTPR (PRI VASP≤10%) as the strongest predictor of bleeding complications in patients treated with thienopyridines. This marker could be useful for tailored therapy and bleeding prevention. [1]: pending:yes