Myocardial Infarction Pathology

The gross specimen of the heart shown above demonstrates a pale, discolored area on the anterior wall, consistent with myocardial necrosis. The inset depicts a coronary artery with significant luminal narrowing. Which of the following is the most likely underlying pathological process leading to these findings?

A 58-year-old man from Mumbai presents to the emergency department with acute onset chest pain radiating to the left arm for the past 3 hours. He has a history of hypertension and smoking. On examination, blood pressure is 95/60 mmHg, heart rate 110/min, and respiratory rate 24/min. ECG shows ST elevation in leads II, III, and aVF with reciprocal ST depression in I and aVL. Cardiac troponin I is elevated at 2.8 ng/mL (normal <0.04). On coronary angiography, a complete thrombotic occlusion of the right coronary artery is identified. Which of the following pathological changes would be MOST prominent in the myocardium at this 3-hour timepoint?

A 62-year-old woman from Delhi presents with acute anterior wall myocardial infarction. She undergoes successful primary percutaneous coronary intervention (PCI) to the left anterior descending artery 90 minutes after symptom onset. Four days later, she develops acute decompensated heart failure with pulmonary edema. Echocardiography reveals a thin-walled, dyskinetic bulge in the anteroapical region of the left ventricle. Which of the following pathological processes is MOST likely responsible for the acute ventricular dysfunction at this 4-day timepoint?

A 58-year-old man with a 2-day history of anterior wall myocardial infarction presents to the emergency department with acute dyspnoea, orthopnoea, and a new pansystolic murmur at the apex. Chest X-ray shows pulmonary oedema. Echocardiography reveals a ruptured papillary muscle with severe mitral regurgitation and an ejection fraction of 35%. What is the most appropriate immediate next step in management?

Which histopathological feature best distinguishes acute myocardial infarction (0–12 hours) from recent myocardial infarction (12–48 hours)?