Angiographic thrombus burden classification in patients with ST-segment elevation myocardial infarction treated with percutaneous coronary intervention

The presence of thrombus is associated with adverse clinical outcomes. Our aim was to develop a classification of thrombus burden (TB) in patients with ST-segment elevation myocardial infarction (STEMI). METHODS: We retrospectively analyzed 900 consecutive patients treated with percutaneous coronary intervention for STEMI. Drug-eluting stents were used in 90.1. TB was graded (G) as G0 ≤ no thrombus, G1 ≤ possible thrombus, G2 ≤ small [greatest dimension ≤ 1/2 vessel diameter (VD)], G3 ≤ moderate (> 1/2 but < 2VD), G4 ≤ large (≥ 2VD), G5 ≤ unable to assess TB due to vessel occlusion. Patients with G5 were reclassified to a thrombus category after flow achievement either with a guidewire or a small (1.5 mm) balloon. The incidence of major adverse cardiac events (MACE) - defined as death, myocardial infarction and infarct-related artery revascularization - was computed using the Kaplan-Meier method. RESULTS: Median duration of follow-up was 18.5 months. G5 patients constituted 57.7 of all patients and reclassification was achieved in 97.9. TB after reclassification was G0, 8.1; G1, 19; G2, 24.5, G3,16.6, G4, 30, G5, 1.9. The 2-year cumulative MACE-free survival was comparable in G1, G2, G3 (84.5, 85.9 and 87 respectively, p ≤ 0.83), while G0 (75.8) and G4 (75) did significantly worse (p ≤ 0.001). After stratification in two groups of small (G0ĝ€"3) and large (G4) TB, the latter was found to be an independent predictor for 2-year mortality (HR: 1.66, 95 CI: 1.04-2.68, p ≤ 0.035) and MACE rate (HR: 2.04, 95 CI: 1.44-2.88, p < 0.001). CONCLUSIONS: In patients with STEMI, TB can be reliably estimated in occluded infarct-related arteries. Large thrombus (≥ 2 VD) is a significant independent predictor for mortality and MACE.