Histopathological features of aspirated thrombi after primary percutaneous coronary intervention in patients with ST-elevation myocardial infarction.

Background: Plaque disruption with superimposed thrombus is the predominant mechanism responsible for the onset of acute coronary syndromes. Studies have shown that plaque disruption and thrombotic occlusion are frequently separated in time. We established the histopathological characteristics of material aspirated during primary percutaneous coronary intervention (PCI) in a large consecutive ST-elevation myocardial infarction (STEMI) population.

Methodology/principal Findings: Thrombus aspiration during primary PCI was performed in 1,362 STEMI patients. Thrombus age was classified as fresh (<1 day), lytic (1-5 days), or organized (>5 day). Further, the presence of plaque was documented. The histopathological findings were related to the clinical, angiographic, and procedural characteristics. Material could be aspirated in 1,009 patients (74%). Components of plaque were found in 395 of these patients (39%). Fresh thrombus was found in 577 of 959 patients (60%) compared to 382 patients (40%) with lytic or organized thrombi. Distal embolization was present in 21% of patients with lytic thrombus compared to 12% and 15% of patients with fresh or organized thrombus.

Conclusions/significance: Material could be obtained in 74% of STEMI patients treated with thrombus aspiration during primary PCI. In 40% of patients thrombus age is older than 24 h, indicating that plaque disruption and thrombus formation occur significantly earlier than the onset of symptoms in many patients.