Acute and sub-acute stent thrombosis: Frequency, predictors and features in patients undergoing primary percutaneous intervention at a tertiary care cardiac centre

OBJECTIVES: To assess the frequency of early (acute and sub-acute) stent thrombosis (ST) after primary percutaneous coronary intervention (pPCI) and to identify its potential predictors. BACKGROUND: ST is a serious clinical event associated with a high mortality rate. A very limited data are available regarding the incidence rate of early ST after pPCI and its predictors, especially for Pakistani population. METHODS: Study included consecutive patients who underwent primary PCI. Telephonic follow-ups were made to obtain 30-days outcomes including ST, mortality, and re-occurrence of symptoms. ST was defined as per the standardized definition proposed by the Academic Research Consortium and classified as acute (during the procedure) and sub-acute (within 30 days). RESULTS: A total of 569 patients were included with 80.5% (485) male patients. The stent thrombosis (acute or sub-acute) was observed in 33 (5.8%) patients out of which 3 (9.1%) were definite ST while remaining 30 (90.9%) were probable ST. Patients who develop ST were predominantly male, hypertensive, diabetic, with reduced pre PCI LVEF (%) and Killip Class. A significantly higher in-hospital mortality rate was observed in patients with ST as compared to without ST, 36.4% (12/33) vs. 0.2% (1/536); p-value < 0.001 respectively. Killip Class (III-IV) was found to be the independent predictor of ST with an adjusted odds ratio of 5.2 [1.76-15.32]. CONCLUSIONS: Early stent thrombosis (ST) is relatively frequent in patients undergoing primary PCI. Diabetic and hypertensive patients are at an increased risk of ST and presentation of patients in Killip Class III-IV is an independent predictor of early ST.