Presence of older thrombus is an independent predictor of long-term mortality in patients with ST-elevation myocardial infarction treated with thrombus aspiration during primary percutaneous coronary intervention.

BACKGROUND: Routine thrombus aspiration is frequently used during primary percutaneous coronary intervention in patients with ST-elevation myocardial infarction to prevent distal embolization. Recently, evidence of clinical benefit was published. In 50% of the ST-elevation myocardial infarction patients with an onset of symptoms <12 hours before, thrombi were shown to be >1 day old. This observation illustrates that plaque rupture and coronary occlusion are significantly separated in time. In the present study, we correlate the presence of fresh versus older thrombus with long-term mortality. METHODS AND RESULTS: Thrombus aspiration was performed in 1315 patients treated with primary percutaneous coronary intervention with 3 devices (Rescue, Export, and Proxis). Aspirated material was fixed in formalin and processed for histopathology. If possible, thrombus age was classified as either fresh only (<1 day) or older (>1 day). We identified fresh thrombus in 552 patients and older thrombus in 372 patients. The cumulative Kaplan-Meier estimate of all-cause mortality at 4 years was significantly higher in patients with older thrombus (16.0%) compared with patients with fresh thrombus (7.4%), with a hazard ratio of 1.82 (95% confidence interval, 1.17 to 2.85; P=0.008). Multivariate analysis identified the presence of older thrombus, in addition to other established predictors, as an independent predictor (hazard ratio, 1.83; 95% confidence interval, 1.14 to 2.93; P=0.01) of long-term mortality. CONCLUSIONS: Our study demonstrates that the presence of older thrombus, in addition to other established predictors, is an independent predictor of long-term mortality in patients with ST-elevation myocardial infarction treated with thrombus aspiration during primary percutaneous coronary intervention.

Plaque instability frequently occurs days or weeks before occlusive coronary thrombosis: a pathological thrombectomy study in primary percutaneous coronary intervention.

BACKGROUND: 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.