Failure of drug eluting stents presented as definite stent thrombosis

Background: Stent thrombosis (ST) risk may persist long after a successful drug eluting stents (DES) implantation. Objective: We evaluated the incidence, timing, and clinical outcomes of patients with early (≤30 days), late (>30-365 days), and very late (>365 days) angiographically proven ST related to DES. Methods: Between 2004 and 2009, 4,396 patients underwent percutaneous coronary interventions (PCI) with DES implantations. This 5-year follow-up study included 38 patients (mean age 60 ± 12 years; 76% males) who were readmitted with confirmed ST diagnoses. Clopidogrel therapy was prescribed for 3-12 months. Clinical follow-ups were conducted at 1 and 6 months following ST events. Results: The overall ST rate was 0.9% (38/4,396); the late ST rate was 0.7%. There were four (11%) early and 34 (89%) late events; the time interval to thrombosis was 21 ± 14 months (range 0.13-60 months). Two patients had stent fractures associated with ST, 37% had diabetes, and 68% presented with ST-elevation myocardial infarctions (MI). One third was treated with clopidogrel at the ST event. Three patients (8%) had recurrent late ST events and two died within 1 month after the ST event (5%). At 6 months, we observed a 26% major adverse cardiac event rate, and the overall cardiac mortality rate was 8%. Conclusions: In our series, ST occurred infrequently (0.9%), mostly between 1 and 3 years after the period recommended for dual anti-platelet pharmacotherapy, and it is associated with substantial clinical consequences.