Clopidogrel and prasugrel are commonly switched in-hospital for patients with myocardial infarction (MI) undergoing percutaneous coronary intervention (PCI), but switching "from initial in-hospital use of clopidogrel to discharge on prasugrel is associated with angiographic and clinical characteristics for increased risk of recurrent thrombotic events... whereas switch[ing] from initial in-hospital use of prasugrel to clopidogrel at discharge is primarily associated with risk of bleeding," according to a study published Aug. 5 in Circulation: Cardiovascular Interventions.

The study used linked data from the ACC's ACTION Registry-GWTG and CathPCI Registry, and looked at the frequency and factors associated with switching between ADPris in clinical practice in 47,040 MI patients treated with PCI, who received either clopidogrel or prasugrel within 24 hours of admission to 361 U.S. hospitals.

Results showed that among 40,531 patients initially treated in-hospital with clopidogrel, 2,125 (5.2 percent) were discharged on prasugrel – increasing in frequency over the course of the study period from 0 percent to 7 percent. Among 6,509 patients initially treated in-hospital with prasugrel, 751 (11.5 percent) were discharged on clopidogrel. The frequency of this switch increased from 6 percent to 18 percent during the first two quarters of the study period and decreased to nine percent by the end.

The authors also found that after initial in-hospital treatment with clopidogrel, switching to prasugrel was most strongly associated with repeat PCI procedures during hospitalization, angiographic and clinical characteristics predictive of higher risk of recurrent thrombotic events, and affordability of the drug with private health insurance coverage. For those with initial in-hospital treatment with prasugrel, switching to clopidogrel was most strongly associated with in-hospital bleeding events and clinical characteristics predictive of bleeding.

Moving forward, the authors note that "additional studies are required to assess the clinical implications of switching ADP receptor inhibitors on patient outcomes."

Keywords: Registries, Myocardial Infarction, Platelet Aggregation Inhibitors, Insurance Coverage, Receptors, Purinergic P2, Thiophenes, Ticlopidine, Piperazines, Hospitalization, Purinergic P2Y Receptor Antagonists, Percutaneous Coronary Intervention, National Cardiovascular Data Registries, ACTION Registry, CathPCI Registry