Impact of Timing of P2Y12 Inhibitor Loading Doses on Revascularization in STEMI

Introduction: Use of P2Y12 inhibitors is an integral part of the management of patients with ST-elevation myocardial infarction (STEMI) who undergo percutaneous intervention (PCI) to prevent stent thrombosis; however, there is limited data about the timing of administration of the loading dose prior to stent deployment. The aim of this study is to evaluate the difference in revascularization rates in patients with STEMI who received P2Y12 inhibitor loading doses in the cardiac catheterization laboratory versus in the emergency department (ED).


Methods: This was a retrospective cohort study conducted in two cardiac catheterization laboratory certified hospitals within the same health system. Adult patients who presented to the ED with a diagnosed STEMI and underwent PCI between December 2023 to December 2024 were included. Data was analyzed using multivariate logistic regression including covariates for age, sex, cardiogenic shock, and left anterior descending artery (LAD) as the culprit vessel. The primary outcome measure was thrombolysis in myocardial infarction (TIMI) flow score < 3.


Results: Of the 292 patients identified, 190 patients met inclusion criteria for analysis. A total of 141 patients received P2Y12 inhibitor loading doses in the ED and 49 patients in the cardiac catheterization laboratory. Most patients were male (72.9%) with an average age of 65 years presenting with anterior STEMI (39.7%) with the LAD as the culprit vessel (47.2%) and a mean TIMI risk score of 4.31. Of patients loaded in the ED, 98.6% received ticagrelor compared to 69.4% of cardiac catheterization laboratory patients. Patients loaded in the ED were 17.1% more likely to have TIMI flow score < 3 compared to patients loaded in the cardiac catheterization laboratory (OR 0.829; 95% CI 0.15-6.52; p-value 0.84).


Conclusions: Compared to patients who received loading doses of P2Y12 inhibitors in the ED, there is no significant difference in revascularization based on TIMI flow score in patients who received their loading dose in the cardiac catheterization laboratory. This may support loading patients in the cardiac catheterization laboratory to prevent delaying further intervention, such as coronary artery bypass grafting, in patients unable to undergo PCI. However, further research is needed to support this finding.