Background. Aggressive anti-platelet therapy is needed in patients who underwent coronary angioplasty, hence the combination of Aspirin and Clopidogrel. A lot of studies were done internationally comparing conventional loading dose versus the higher loading dose, but we would like to test if their hypothesis would also apply to Filipinos, in terms of decreased major adverse cardiovascular events and bleeding rates. This study was done to compare 30 days outcome of patients receiving 600mg versus 300mg Clopidogrel loading dose prior to PCI. The primary end points that were determined in each study patient were the occurrence of death, postprocedural myocardial infarction, stroke and target vessel revascularization.
Methods. This is a randomized double blind trial involving patients for percutaneous coronary intervention (PCI). Subjects were randomized in a double blind fashion to receive either Clopidogrel 600 mg loading dose or Clopidogrel 300 mg loading dose given 4 to 6 hours prior to procedure. Complete blood count, Prothrombin time, partial prothrombin time, creatinine kinase MB and troponin-I were measured at baseline; and CKMB and Troponin - I were repeated at 8 or 24 hours after intervention. The primary end points were the 30-day occurrence of death, myocardial infarction (MI), stroke or target vessel revascularization (PCI or CABG).
Results. A total of 115 patients scheduled to undergo percutaneous coronary intervention were randomized to a 600mg (n=58) or 300mg (n=57) group. The primary end point occurred in 51% of patients in the high loading dose versus 85 % of those in the conventional loading dose group (OR 0.19, 95% Cl 0.08 to 0.46, P=O.OOO) and was due entirely to decreased rates of periprocedural MI in the higher loading arm. Troponin-I was significantly higher in the 300mg arm (4.3%) compared to the 600mg arm (2.5%) with a P value 0.007.
Conclusions. Pre-treatment with a 600mg loading dose of Clopidogrel 4 to 6 hours before the procedure is safe compared with the conventional 300mg dose, it significantly reduced the primary composite end point in the higher loading arm. It has greater significance in terms of lower periprocedural MI in patients undergoing percutaneous coronary intervention given 600mg loading dose of Clopidogrel. This study may support its routine use in elective coronary angioplasty, and have influence in future studies.