Resistance to Clopidogrel among Iranian Patients Undergoing Angioplasty Intervention

To study the resistance to standard dosage of clopidogrel among Iranian patients following percutaneous coronary intervention measured by platelet aggregation test. Patients undergoing percutaneous coronary intervention in Imam Hussein Medical center, Tehran, Iran, who were under treatment with aspirin, but had no history of clopidogrel usage, entered the study. Patients received standard dosage of clopidogrel (Plavix(®), Sanofi, France, 600 mg loading dose and 75 mg/day afterward). Platelet aggregation was measured using light transmission aggregometer. The response to the drug was categorized as complete resistance (platelet aggregation decreased less than 10%), intermediate resistance (platelet aggregation decreased between 10 to 30%) and complete response (platelet aggregation decreased to 30% or more). All patients were evaluated for major adverse cardio vascular events one month after the angioplasty based on MACE criteria by phone contact. Thirty-one patients with a mean age of 59 ± 13 entered the study. Sixty-five percent of patients showed complete response to clopidogrel (95% CI: 45% to 81%), 22% showed intermediate resistance (95% CI: 10-41%) and 13% showed complete resistance (95% CI: 4-30%). One month after the angioplasty, no major adverse cardiovascular event was recorded. Based on our findings, it seems that there is no major difference between Iranian population and other studies regarding the resistance to clopidogrel. Due to the limited number of participants in our study, further investigations with higher number of patients are recommended to more precisely calculate the percentage of resistance among Iranian patients.