The goal of this clinical trial is to learn if adding standardized manual thrombus aspiration to primary percutaneous coronary intervention (PPCI) works better to improve heart health outcomes and protect long-term heart function in adults with acute ST-segment elevation myocardial infarction (STEMI) and a high blood clot burden in the heart's arteries. The main questions it aims to answer are:
* Does PPCI plus manual thrombus aspiration lower the risk of serious heart problems one year after treatment, compared to PPCI alone? * Can manual thrombus aspiration better protect long-term heart function in people with a high blood clot burden? Researchers will compare two groups of participants-one group getting PPCI plus manual thrombus aspiration and one group getting only PPCI-to see if the aspiration treatment leads to fewer serious heart problems, better long-term heart function, and similar safety (including no higher risk of stroke).
Participants will:
* Have a heart artery scan (coronary angiography) to confirm a high blood clot burden * Be randomly assigned to one of the two treatment groups for their PPCI procedure * Complete follow-up checks at 30 days, 6 months, and 1 year after treatment, including heart function tests (like echocardiograms) * Have heart magnetic resonance (CMR) scans if selected, to measure heart tissue damage and heart function * Have their heart health status and any adverse events recorded throughout the study
Aged ≥18 years old, diagnosed with acute ST-segment elevation myocardial infarction (STEMI) (chest pain plus ST-segment elevation ≥1mm or new-onset left bundle branch block [LBBB]) with symptom onset < 12 hours.
Planned to undergo primary percutaneous coronary intervention (PPCI).
High thrombus burden in the target vessel (TIMI thrombus grade ≥3, or visible floating thrombus) confirmed by coronary angiography.
Reference diameter of the target vessel ≥2.75mm, with the lesion suitable for the passage of an aspiration catheter.
Cardiogenic shock (Killip class IV) or requiring mechanical circulatory support.
A history of previous coronary artery bypass grafting (CABG).
Concurrent intervention required for non-culprit vessels.
Severe bleeding tendency (e.g., INR > 2.5, platelet count < 50×10⁹/L).