Immunohistochemical characteristics of coronary thrombi in ST-elevation myocardial infarction.

Background And Aims: The dynamics and implications of intracoronary thrombus constituency in patients with ST-segment elevation myocardial infarction (STEMI) are not fully understood. We evaluated the expression of CD34, CD61and factor VIII surface markers in thrombi of patients with STEMI and its association with clinical and angiographic characteristics and major adverse cardiovascular events (MACE).

Methods: Patients presenting with STEMI undergoing aspiration thrombectomy during primary percutaneous coronary intervention (pPCI) were included. Morphological, histopathological and immunohistochemical aspects of thrombi were assessed by two pathologists blinded to clinical variables and outcomes.

Results: The mean age of the 245 patients included was 58 ± 12 years old, and 70 % were men. Regarding the thrombi microscopic patterns, 61 % were classified as recent, 20 % as lytic and 19 % as organized. There were higher levels of the CD61 index in patients with a history of heart failure. Smokers presented lower CD61 positive cells and CD61 index, but this association did not remain significant after multivariable analysis. There was an inverse correlation between CD61 positive cells and CD61 index with the time from onset of pain to the first medical contact, but no other significant association amongst clinical characteristics and antigenic expression. There was higher expression of the CD61 antigen in patients with in-hospital MACE, but statistical significance was borderline (p = 0.06).

Conclusions: In this cohort of patients with STEMI, immunohistochemistry of coronary thrombus showed a significantly higher platelet content in patients with previous heart failure and a trend in those with in-hospital MACE. Thrombus' platelet content was inversely related to ischemic time.