Effect of upstream clopidogrel treatment in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention.

AIMS Immediate treatment with a loading dose of clopidogrel at diagnosis of ST-segment elevation myocardial infarction (STEMI) is recommended by ESC/AHA/ACC guidelines in patients eligible for primary percutaneous coronary intervention (PCI). However, the evidence for this practice is scarce. METHODS AND RESULTS All patients who underwent PCI for STEMI in Sweden between 2003 and 2008 were identified from the national Swedish Coronary Angiography and Angioplasty Registry (SCAAR). Patients with concomitant warfarin treatment and patients not having received aspirin upstream were excluded, leaving 13 847 patients for the analysis. Groups were compared for death and myocardial infarction (MI) during 1-year of follow-up using Cox regression models with adjustment for differences in baseline characteristics by propensity score methods. The combined primary endpoint of death or MI during 1-year follow-up occurred in 1325 of 9813 patients with upstream clopidogrel and in 364 out of 4034 patients without upstream treatment. After propensity score adjustment, a significant relative risk reduction (HR 0.82, 95% CI 0.73-0.93) in death/MI at 1 year was observed. The secondary endpoint of total 1-year death was significantly reduced (HR 0.76, 95% CI: 0.64-0.90), while the incidence of 1-year MI did not show any significant reduction (HR 0.90, 95% CI 0.77-1.06). Similar results were observed in multivariate analysis on top of propensity scoring and in sensitivity analyses excluding patients without clopidogrel and aspirin at discharge. CONCLUSION This large observational study suggests that upstream clopidogrel treatment prior to arrival at the catheterization lab is associated with a reduction in the combined risk of death or MI as well as death alone in patients with STEMI treated with primary PCI.