Intra-procedural stent thrombosis: a new risk factor for adverse outcomes in patients undergoing percutaneous coronary intervention for acute coronary syndromes.

OBJECTIVES: The aim of this study was to examine the incidence, correlates, and consequences of intra-procedural stent thrombosis (IPST) in patients with acute coronary syndromes (ACS).

BACKGROUND: Stent thrombosis (ST) is a rare but serious complication of percutaneous coronary intervention (PCI). The Academic Research Consortium definition of ST excludes events occurring during PCI.

METHODS: Angiograms from the ACUITY (Acute Catheterization and Urgent Intervention Triage StrategY) and HORIZONS-AMI (Harmonizing Outcomes with RevascularIZatiON and Stents in Acute Myocardial Infarction) trials were reviewed frame-by-frame at an independent core laboratory for the occurrence of IPST. Patients with versus without IPST were compared to identify baseline characteristics associated with IPST and demonstrate the independent association between IPST and adjudicated events at 30 days and 1 year.

RESULTS: Intra-procedural ST occurred in 47 (0.7%) of 6,591 patients. The occurrence of IPST was associated with ST-segment elevation myocardial infarction presentation, high white blood cell count, treatment of thrombotic and bifurcation lesions, bivalirudin monotherapy, bail-out IIb/IIIa inhibitor use, and implantation of bare-metal (rather than drug-eluting) stents. Major adverse ischemic events were markedly higher in patients with versus without IPST, including mortality at 30 days (12.9% vs. 1.4%, p < 0.0001) and 1 year (12.9% vs. 3.1%, p < 0.0001). Out-of-lab Academic Research Consortium definite or probable ST also occurred significantly more often among IPST patients at 30 days (17.4% vs. 1.8%, p < 0.0001) and 1 year (19.9% vs. 2.7%, p < 0.0001). Intra-procedural ST was a significant independent predictor of 1-year mortality (hazard ratio: 3.86, 95% confidence interval: 1.66 to 9.00, p = 0.002).

CONCLUSIONS: Intra-procedural ST is a relatively rare complication of PCI in ACS but is strongly associated with subsequent out-of-lab ST and mortality. Intra-procedural ST should be considered as a distinct category of ST and routinely reported, particularly for ACS patients.