Comparison of benefit and safety between different loading dose of clopidogrel on elderly patients undergoing primary percutaneous cronary intervention for ST-segment elevation myocardial infarction

Background Despite the proven benefit of 600-mg loading dose of clopidogrel in patients with acute ST-segment elevation myocardial infarction (STEMI) who undergo primary percutaneous cronary intervention (PCI), there is still concern about its benefit and safety on elderly population. Methods Data of 172 consecutive elderly patients (≥75 years) with STEMI who underwent primary PCI at Guangdong Provincial Cardiovascular Institute from January 2008 to December 2011 were retrospectively collected. Patients were divided into 600-mg loading clopidogrel group and 300-mg clopidogrel group accoring to the loading dose of clopidogrel before primary percunaeous coronary intervention(PCI). Enzymatic myocardial infarction size estimated by peak creatine kinase-myocardial band (CK-MB) and patency of the infarct-related artery (IRA) were compared. Thirty-day major adverse cardiac events (MACEs), which consist of death, nonfatal myocardial infarction (MI), nonfatal stroke, target vessel revascularization (TVR) or stent thrombosis (ST) were compared to assess the efficacy of different loading dose. Bleeding information was compared as well to assess the safety of different pretreatment stragety before primary PCI. Results 96 patients were adminstered with 600-mg loading clopidogrel before primary PCI while 76 were administered with 300-mg. Patency of the IRA was significantly higher in patients administered with 600-mg loading clopidogrel therapy as compared with those who received 300-mg loading clopidogrel (94.8% vs. 85.5%, P = 0.038). 600-mg loading dose of clopidogrel was associated with lower incidence of 30-day MACEs compared with 300-mg loading dose of clopidogrel (8.3% vs. 19.7%, P = 0.029) while did not increase the risk of TIMI major (3.1% vs. 3.9%, P = 0.770) and minor bleeding (10.4% vs. 6.6%, P = 0.376). Conclusion 600-mg loading clopidogrel improves final patency of the IRA and clinical outcome as compared with 300-mg loading clopidogrel without increasing bleeding hazard.