Establishment of a Reproducible Porcine Myocardial Infarction Model Using a Mini-Thoracotomy Approach

Preclinical porcine models of myocardial infarction (MI) are essential for cardiovascular research but often require lengthy surgeries with variable outcomes. We developed a minimally invasive mini-thoracotomy approach to maximize procedural success, minimize operative time, and ensure reproducible infarct induction. Eleven Lanyu Miniature Pigs (25-30 kg) were assigned to an MI group (n = 7) or sham control group (n = 4). MI was induced by permanent left anterior descending (LAD) coronary artery ligation via mini-thoracotomy. Six of seven MI pigs (85.7%) survived, with a mean skin-to-skin operative time of 35.83 ± 2.86 minutes, whereas all sham controls survived without complications. Infarction was confirmed by post-ligation ST-segment elevation and pathological Q waves. Serial echocardiography and speckle-tracking strain analysis at baseline, 1 week, and 3 months revealed consistent regional systolic dysfunction in the MI group, though inter-animal variability was observed in certain functional parameters. Cross-sectional area-based ejection fraction was significantly reduced at the papillary muscle and apical levels by 1 week, persisting through 3 months. Speckle-tracking showed corresponding reductions in radial strain, particularly apically. Progressive ventricular remodeling was evident from an increased left ventricular mass index, and Masson's trichrome staining confirmed extensive myocardial fibrosis distal to the ligation sites (mean fibrotic area 25.6 ± 4.3%). Sham controls retained preserved structure and function throughout. In conclusion, this minimally invasive porcine MI model provides a highly feasible, rapid, and reproducible translational platform, integrating surgical accessibility with robust functional and histological validation for investigating post-infarction remodeling and evaluating cardiovascular therapeutics.