Idiopathic Thrombocytopenic Purpura Correlates with a Lower Rate of ST-Elevation Myocardial Infarction

Abstract

Background: Platelets are important parts in the pathogenesis of myocardial infarction (MI). In order to study the role of platelet count in MI, we hypothesize that patients with acquired thrombocytopenia such as idiopathic thrombocytopenic purpura (ITP) may have lower risk of MI. Using a large database, we studied any correlation between the presence of ITP and ST Elevation Myocardial Infarction (STEMI). Method: The Nationwide Inpatient Sample (NIS) was used for this study. Using the available NIS database from the years 2001-2011, we analyzed the correlation between STEMI and ITP utilizing International Classification of Diseases, ninth revision, and Clinical Modification (ICD-9-CM) ICD-9 codes. We used uni- and multivariate analysis adjusting for risk factors. Data was extracted from 106,653 patients with ITP and 79,636,090 patients without ITP. Results: Between the years of 2002 and 2011, we were able to observe significant differences between the patients with ITP and those without. We found that the risk of STEMI is significantly reduced in patients with ITP in uni and multivariate analysis in every year of the 10-year period. For example, we found that in 2002 STEMI occurred in 0.09% of patients with ITP vs. 0.13% without ITP (p<0.007). Then in another example in 2011, the same percentage of ITP patients experienced STEMI with a prevalence of 0.09% vs. 0.15 in patients without ITP (p<0.005). This reduction remains significant after multivariate adjustment Conclusion: Based on our large database, the presence of ITP appears to be associated with a lower risk of STEMI. This finding suggests that platelet counts play important role in the pathogenesis of STEMI and low platelet count may exert protective effect from STEMI.