Authors:
M.C.A. Kramer¹, A.C. Van Der Wal¹, K.T. Koch¹, R.J. Van Der Schaaf¹, J.P. Henriques¹, J. Baan¹, Z.H. Rittersma¹, J.J. Piek¹, J.G.P. Tijssen¹, R.J. De Winter¹, ¹Academic Medical Center - Amsterdam - Netherlands,

Background: Routine thrombus aspiration is frequently used during primary percutaneous coronary intervention (PCI) to prevent distal embolization, but has not been shown to improve long-term clinical outcome. We have previously shown that thrombus age is more than 1 day old in 50% of patients with ST-elevation myocardial infarction (STEMI) and onset of symptoms less than 12 hours before. This observation illustrates that plaque rupture and coronary occlusion are events that are significantly separated in time. In this analysis, we correlate the presence of fresh thrombus versus older thrombus with long-term mortality.

Methods: Thrombus aspiration was performed in 1,315 patients undergoing primary PCI for ST-elevation myocardial infarction, with three different devices (Rescue, Export and ProxisTM). Macroscopic material was immediately fixed in formalin, stained and subsequently confirmed by pathology. If possible, thrombus age was classified as fresh only (less than 1 day) or older (more than 1 day).

Results: We identified fresh thrombus in 551 patients and older thrombus in 371 patients. Follow-up up to 4 years was complete in 99%. All-cause mortality at 4-year was significantly lower in the patients with fresh thrombus (7.5%) compared with the patients with older thrombus (16.1%) (P=0.008). Multivariate analysis showed that thrombus age was an independent predictor of 4-year mortality, with a hazard ratio of 0.53 (95% CI 0.35 to 0.86).

Conclusions: We demonstrate that in STEMI-patients undergoing primary PCI, thrombus age is an independent predictor of 4-year mortality. Patients with fresh thrombus had a, nearly 50% reduction in long-term mortality compared with patients with older thrombus. This result suggests that the benefits of adjunctive use of mechanical devices during primary PCI might be dependent on thrombus composition and thrombus age.