Personalized ADP-receptor inhibition strategy and outcomes following primary PCI for STEMI (PASTOR study).

Background: Adequate antiplatelet therapy in patients with myocardial infarction with ST-elevation (STEMI) is vital in order to avoid ischemic complications. However, especially with the novel potent oral drugs, bleeding is a major concern. We aimed to investigate whether STEMI patients switched to novel ADP receptor inhibitors due to high platelet reactivity (HPR) on clopidogrel have similar outcomes compared to patients with adequate response to clopidogrel.

Methods: A prospective cohort of 175 STEMI patients (mean age 62.3 years) undergoing primary PCI were included in the PASTOR study. Patients were loaded with 600 mg clopidogrel before the index PCI procedure. Bedside VerifyNow P2Y12 platelet function testing was performed the following morning.

Results: 46 patients (26.3%) were found to have HPR on clopidogrel (PRU>235) and were switched to novel ADP receptor antagonists. The remaining 129 patients were treated with clopidogrel. The mean duration of dual antiplatelet therapy (DAPT) was 6.7 months. Duration of entire follow-up of patients was approximately 2 years. Major adverse cardiac events (MACE) while patients were on DAPT occurred in 7.0% in the clopidogrel group compared to 8.7% in the novel ADP receptor antagonist group (p=0.70). No differences were observed between groups off-DAPT either.

Conclusions: Following primary PCI for STEMI, patients with adequate response to clopidogrel show similar outcomes compared to patients switched to novel ADP receptor antagonists due to HPR on clopidogrel. Platelet reactivity testing can be used to guide the choice of antiplatelet therapy in patients with STEMI treated by primary PCI.