Impact of baseline thrombocytopenia on the early and late outcomes after ST-elevation myocardial infarction treated with primary angioplasty: Analysis from the Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) trial

Background Thrombocytopenia (TP) is a common abnormality in patients presenting with acute coronary syndrome. Whether baseline TP has any influence on the outcome of patients treated with primary angioplasty for acute myocardial infarction is unknown. Methods We sought to detect the impact of baseline TP on the early and late outcomes of patients with ST-elevation myocardial infarction in the HORIZONS-AMI trial that included a protocol of immediate angiography and primary percutaneous coronary intervention. Results Baseline TP was found in 4.2% of patients and was associated with a higher incidence of cardiovascular mortality, major bleeding, and major cardiovascular events at short-and long-term follow-up. The 30-day rates of death, major bleeding, major cardiac events, and major cardiac events plus major bleeding were 6.2%, 11.9%, 9.6%, and 18.5% in the TP group, respectively, compared with 2.1%, 7%, 5.2%, and 10.8% in those without TP (P < .05 for all). Similarly, event rates at 2 years were 11.3%, 12.7%, 24.7%, and 30.8% compared with 5.1%, 7.9%, 18.5%, and 23.3% (P < .05). By multivariate analysis, baseline TP was an independent predictor of 30-day net adverse clinical events but not of any 2-year events. Conclusions We found that baseline TP in patients with ST-elevation myocardial infarction undergoing routine angiography and primary percutaneous coronary intervention is strongly associated with early adverse events and is a maker of late events, related to both ischemia and bleeding. (Am Heart J 2011; 161: 391-6.)