Microvascular Dysfunction Related to Progressive Left Ventricular Remodeling due to Chronic Occlusion of the Left Anterior Descending Artery in an Adult Porcine Heart

Occlusion of a major coronary artery induces myocardial infarction (MI), leading to left ventricle (LV) remodeling due to progressive microvasculature dysfunction. Irreversible impairment in microvascular function has been suggested to extend from the infarcted region into the infarct-border or remote regions, depending on the time to revascularization. Our aim was to determine whether the occlusion of a major coronary artery induces microvascular dysfunction in the adjacent area perfused by intact coronary arteries using a porcine model for chronic total occlusion of the left anterior descending artery (LAD). MI was induced via an ameroid constrictor ring around the LAD in adult Gottingen pigs (Sus scrofa domesticus. n = 5). Age-matched normal pigs were treated as controls (n = 3). Cardiac magnetic resonance showed reduced systolic regional wall motion in the left circumflex (LCx) and right coronary artery (RCA) territories, with a progressively worsening motion in the infarction-adjacent area over an eight-week period. On N-13-ammonia positron emission tomography (PET), myocardial blood flow (MBF) during hyperemia was significantly greater in the LCx and RCA territories (particularly in the infarction-adjacent area) compared to that in the LAD territory at four weeks after infarct induction. Subsequently, the flow significantly decreased, approaching that in the LAD territory at eight weeks after infarct induction. Fluoroscopy-guided pressure-wire studies showed significantly higher microvascular resistance in the LCx area at eight weeks compared to that in controls. Electron microscopy showed endothelium swelling and microvasculature disruption in areas adjacent to the LCx and RCA territories. Anterior MI caused coronary microvascular dysfunction in the adjacent area, associated with a reduced MBF and regional wall motion.