Thrombus aspiration reduces myocardial infarct size in patients with STEMI and high thrombus burden

Abstract Background Microvascular obstruction (MVO) represents a major determinant of prognosis in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI). Despite the notable advancements in reperfusion strategies, MVO remains a critical challenge, contributing to unfavorable left ventricular remodeling and elevated long-term mortality. Thrombus aspiration (TA) has been proposed as a potential strategy to minimize distal embolization and reduce MVO, but its effect on myocardial scar and cardiac remodeling remains debated. Purpose The objective of this study was to investigate whether TA influences myocardial tissue characteristics and left ventricular remodeling in patients with STEMI. To this end, changes in myocardial scar, edema, and MVO were assessed on cardiac magnetic resonance (CMR) scans performed during the acute phase and at a 6–24 months follow-up. Methods A retrospective analysis was conducted on STEMI patients treated with PPCI at a single high-volume center from January 2011 to July 2019. Patients who underwent index and follow-up CMR scans were enrolled. CMR assessments included left ventricular function, infarct size (late gadolinium enhancement, LGE), myocardial edema (T2-weighted imaging), and MVO. The primary endpoint was the reduction in infarct size. Results A total of 130 patients were enrolled; 84 patients underwent TA, while 46 received PPCI alone. As expected, patients undergoing TA had worse baseline clinical characteristics, including a significantly higher thrombus burden (Thrombus Scale 5 5;5 vs. 3 2;5, p0.001) and a greater frequency of pre-procedural TIMI 0 flow (79.8% vs. 41.3%, p0.001). Additionally, MVO was more frequently observed in the TA group (44.6% vs. 25%, p=0.03). Baseline CMR scans revealed a larger infarct size (LGE: 24.2% vs 17.5%, p=0.001) and more extensive myocardial edema (38% vs 27%, p=0.04) in patients undergoing TA. During follow-up, those in the TA group experienced a greater reduction in myocardial scar (-5.49g -23.98; 1.5 vs. -1.59g -8.7; 2.21, p=0.05) and myocardial edema (-54.4g -78; -39.2 vs. -47.3g -57.9; -19.5, p=0.05). The reduction in LGE was particularly evident among individuals with a high thrombus burden (Thrombus Scale 3) and baseline MVO (-11.28g -27.03; -0.20 vs. -1.78g -6.50; 0.25, p=0.09), although statistical significance was not reached. Conclusions Follow-up CMR scans demonstrated favorable reductions in infarct size and myocardial edema in STEMI patients treated with TA, particularly among those with high thrombus burden, despite their poor clinical baseline characteristics. These findings suggest that TA may contribute to improved myocardial tissue recovery in high-risk STEMI patients. These observations underscore the necessity for additional prospective studies to refine patient selection and ascertain whether TA can provide long-term benefits in this population.