Increased long term rates of stent thrombosis and mortality in patients given clopidogrel as compared to ticlopidine following coronary stent implantation

BACKGROUND: Clopidogrel has largely replaced ticlopidine following coronary stent implantation. Recently, concern has been raised regarding the possibility of excess long term mortality in patients given clopidogrel rather than ticlopidine following coronary stenting. METHODS: We studied 1519 consecutive patients who underwent 2020 stent implantations and were discharged on dual antiplatelet regimens of either aspirin and ticlopidine or aspirin and clopidogrel given for up to 4 weeks. Thrombotic stent occlusion (TSO) was defined as ST elevation myocardial infarction in the stented artery territory associated with angiographic demonstration of complete stent occlusion. Mortality follow up was obtained for all patients by linkage to the Population Register. Follow up duration was 12 months. RESULTS: TSO occurred in 37 stents at a median of 29 days post procedure. Of these cases, six occurred in the ticlopidine group (0.7%) and 31 in the clopidogrel group (2.8%) (p<0.01). The median time to TSO was 34 days and 28 days in ticlopidine and clopidogrel treated patients, respectively (p<0.01). After controlling for multiple demographic, clinical and angiographic variables clopidogrel (vs. ticlopidine) treatment remained the sole predictor of TSO (OR: 5.4, 95% CI=1.2-24.1, p=0.028). Of even more concern, clopidogrel treatment was associated with an increased risk of 1 year mortality (OR: 1.8, 95% CI=1.2-2.8). CONCLUSIONS: Long term follow up after stent implantation in patients receiving the traditional 2-4 weeks course of dual antiplatelet therapy reveals increased rates of TSO and mortality in patients given clopidogrel as opposed to ticlopidine. Whether longer treatment with clopidogrel will change these observations deserves further study.