Timing of thrombotic events in patients receiving 2 weeks of clopidogrel therapy post bare metal coronary artery stenting: a New Zealand retrospective study.

OBJECTIVE: To investigate if increased thrombotic events occurred after cessation of a 2-week course of clopidogrel treatment in patients who had implantation of bare metal stent. SETTING: Dunedin Public Hospital, a tertiary referral centre in New Zealand. PATIENTS: 1000 consecutive patients undergoing percutaneous coronary intervention (PCI) with stent implantation from January 2000 to October 2003 were analysed. Those who had successful implantation of bare metal stent without clinical events in the first 24 hours and who received 2 weeks of clopidogrel treatment were included in the study (n=983). MAIN OUTCOME MEASURES: Stent thromboses between 24 hours and 6 weeks post PCI. RESULTS: There were 13 (1.3%) stent thromboses between 24 hours and 6 weeks post PCI, resulting in 3 deaths (23%), 2 ST-elevation acute coronary syndrome [ACS] (15%), and 8 non-ST elevation ACS (62%). The median time for stent thrombosis was 18 +/-s 14 days. Five of the 13 cases (38%) of stent thrombosis occurred after the first 2-weeks (1 in week 3, 1 in week 5, 3 in week 6), and all had predisposing factors for stent thrombosis (2 with stent length > or = to 30 mm, 3 with stent diameter < or = to 2.5mm and 2 with bifurcation stenting). CONCLUSION: Five of 13 (38%) stent thromboses occurred in week 3 to week 6 after cessation of a 2-week course of clopidogrel post bare metal stenting.