Infarcts can be even more extensive than this. Anomalous origin of left coronary artery from pulmonary trunk. The same risk factors as for atherosclerosis, fatty diets, hypertension, diabetes, smoking, etc. Low incidence in women rises in postmenopausal years, when estrogen relacement is protective. Lesions not visible before 18-24 hours after onset.
Earliest change is a poorly defined pale area, some with hemorrhagic changes.
Area defined better with time, turning yellow with a pink margin of organizing tissue, and, finally, a discrete scar. Frank coagulative necrosis at 24-72 hours, loss of fiber nuclei, and heavy neutrophilic infiltrate. Complications include arrhythmias, shock, heart failure, cardiac rupture, and pulmonary emboli. Late complications are mural thrombi and aneurysms. Cotran RS etal.