Cardiac magnetic resonance in acute myocardial infarction undergoing thrombus aspiration

Background: Microvascular obstruction (MVO) is a major prognostic determinant in STEMI. While thrombus aspiration (TA) during primary percutaneous coronary intervention (PCI) aims to reduce distal embolization and MVO, its impact on long-term myocardial scar and remodeling remains debated. The present study aimed to evaluate the impact of clinically indicated TA on myocardial scar and MVO using cardiac magnetic resonance (CMR) at baseline and 12-month follow-up in STEMI patients treated with PCI. Methods: In this single-center observational cohort study, consecutive STEMI patients treated with primary PCI ± TA who underwent CMR at baseline and at 12 months were enrolled. CMR parameters included left ventricular volumes, ejection fraction, global longitudinal strain, infarct size (late gadolinium enhancement) and MVO. Results: Among 130 STEMI patients (84 PCI + TA, 46 PCI-alone) enrolled, the TA group had higher baseline thrombus burden (TIMI Thrombus Grade 5 [5;5] vs. 3 (Henriques et al., 2002; Byrne et al., 2023 [2, 5]), p < 0.001), higher MVO prevalence (44.6% vs. 25%, p = 0.03) and larger infarct size [late gadolinium enhancement LGE: 24.2% vs 17.5% of left ventricle (LV) myocardial mass, p = 0.001]. At follow-up CMR, PCI + TA group experienced a greater reduction in myocardial scar (-5.0% [-21.8; 1.4] vs. -3.28% [-17.9; 4.6], p < 0.05), particularly in patients with a high thrombus burden (Thrombus Grade > 3) and baseline MVO (-10.3% [-19.8; -2.5] vs. -3.7% [-9.5; 1.2], p < 0.05). Conclusions: Despite worse baseline clinical and imaging characteristics, STEMI patients treated with TA showed more favorable myocardial tissue recovery at 12 months. These findings suggest that TA may optimize conditions for scar consolidation, particularly in high-risk patients with heavy thrombus burden.