Q. A 60-year-old male patient presented to the emergency department 4 days ago with a complaint of chest pain that began suddenly while he was at rest. The pain was described as a crushing sensation in the center of his chest and radiated to his left arm and jaw. An EKG demonstrated ST-segment elevation in leads V1-V4, and blood tests showed elevated levels of troponin, confirming the diagnosis of an acute MI. The patient was taken to the cardiac catheterization laboratory and a catheter was inserted into the femoral artery and guided to the coronary vessels. A coronary angiogram performed revealed a complete occlusion of the left anterior descending artery, and a stent was inserted through the catheter and positioned at the site of the occlusion. The patient is now in the cardiac care unit and has been stable since the procedure. Today, the patient suddenly experiences shortness of breath and chest pain. On physical examination, you detect diffuse bilateral crackles on lung auscultation. His cardiac assessment reveals an S3 gallop with lateral displacement of the point of maximal impulse. You also detect a significant holosystolic murmur heard best at the cardiac apex with radiation to the left axilla. The patient has acutely developed altered mental status, tachycardia, hypotension, tachypnea, hypoxemia, and cyanosis. Based on the information you have at this point in time, which of the following is the most likely cause of this patient’s rapid deterioration?