Acute
ST-elevation myocardial infarction (
STEMI) is caused by sudden occlusive
coronary thrombosis, after plaque disruption; however, a considerable time interval between plaque disturbance and the onset of symptoms has been suggested. We therefore studied the age of intracoronary thrombi, aspirated during angioplasty in patients with acute
STEMI.
METHODS AND RESULTS: Percutaneous intracoronary
thrombectomy during angioplasty was performed in 211 consecutive
STEMI patients within 6 hours after onset of anginal symptoms. The aspirated material was histologically screened on
thrombus and plaque components, and
thrombus age was classified as fresh (<1 day), lytic
thrombus (1 to 5 days), and organized
thrombus (>5 days). In all patients, intracoronary-derived material was retrieved in the filter of the collection bottle.
Thrombus was identified in 199 (95%) of 211 patients. In 12 patients (5%), only plaque components were identified, and in 85 patients (41%), both
thrombus and plaque material were aspirated. In 18 (9%) of 199 patients, the
thrombus was organized, and in 70 patients (35%), the
thrombus showed lytic changes, whereas in 98 (49%), a completely fresh
thrombus was found. In 14 (7%) of 199 patients, the
thrombus showed combined features of both fresh
thrombus and organized
thrombus.
CONCLUSIONS: In at least 50% of patients with acute
STEMI, coronary thrombi were days or weeks old. This indicates that sudden
coronary occlusion is often preceded by a variable period of plaque instability and
thrombus formation, initiated days or weeks before onset of symptoms.