A 62-year-old man comes to the emergency department due to 2 hours of chest discomfort. He was eating a light dinner when he developed rapidly worsening mid-chest discomfort associated with nausea and weakness. For the last few days, the patient has also experienced "stomach flu" symptoms with episodic nausea and vomiting and decreased oral intake. Two weeks ago, he was diagnosed with an acute inferior wall myocardial infarction and received a bare metal stent to the right coronary artery. His hospital course was uncomplicated. Pre-discharge echocardiogram showed inferior and posterior wall hypokinesis and a left ventricular ejection fraction of 50%.
Temperature is 37.2 C (99 F) , blood pressure is 98/64 mm Hg, and pulse is 55/min. Oxygen saturation is 99% on room air. BMI is 23 kg/m². The patient appears uncomfortable. There is no jugular venous distention and the lungs are clear. A grade 2/6 holosystolic murmur is heard at the apex. The abdomen is nontender with no hepatomegaly. Peripheral pulses are symmetric.
ECG shows sinus bradycardia with 2-mm ST-segment elevation in leads II, III, and aVF.
Which of the following is the most likely diagnosis?

Question

Quizplus · Accepted Answer

This patient is experiencing an acute inferior wall myocardial infarction (MI) due to coronary artery stent thrombosis. Stent thrombosis is most common in the first month following stent placement but may develop at any time. It typically presents as an ST elevation MI and carries a mortality rate of up to 30%. Dual antiplatelet therapy (DAPT) with aspirin and a platelet P2Y12 receptor blocker (eg, clopidogrel, prasugrel, ticagrelor) is recommended for at least 6-12 months following placement of either drug-eluting or bare metal stents (BMS). If necessary, treatment can be limited to 1 month following BMS placement in patients with high bleeding risk, impaired compliance, or planned surgical procedures. Premature discontinuation of DAPT is the most important factor associated with stent thrombosis. This patient's gastroenteritis likely precluded his ability to tolerate DAPT only 2 weeks after BMS placement, placing him at high risk for stent thrombosis. (Choice A) Left ventricular aneurysm represents scarred myocardium due to prior MI. It can cause progressive left ventricular enlargement leading to heart failure, angina, arrhythmias, or mural thrombus embolization. ECG shows persistent ST-segment elevation due to dyskinetic myocardial segments, along with deep Q waves in the same leads (not seen in this patient). (Choice B) This patient has clear evidence of acute myocardial injury on ECG, and his symptoms should not be attributed to noncardiac pain. (Choice C) Some degree of mitral regurgitation (holosystolic murmur at apex) can occur in patients with inferior MI due to papillary muscle dysfunction and/or tethering of posterior mitral leaflet. Papillary muscle rupture typically occurs within 3-5 days after an acute MI, leading to acute severe mitral regurgitation with hypotension and pulmonary edema. The patient has clear lung fields and is not markedly hypotensive, making papillary rupture unlikely. (Choice D) Peri-infarction pericarditis generally occurs within days after acute MI. It is characterized by pleuritic chest pain, a pericardial friction rub, and diffuse ST elevations on ECG. Educational objective: Stent thrombosis typically presents as an ST elevation myocardial infarction, usually within the first month after stent placement. Premature discontinuation of antiplatelet therapy is the most important factor associated with stent thrombosis. __________ References: Stent thrombosis. (http://www.ncbi.nlm.nih.gov/pubmed/20946992) 2014 ACC/AHA guideline focused update on duration of dual antiplatelet therapy in patients with coronary artery disease: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. (http://www.ncbi.nlm.nih.gov/pubmed/27036918)

A 62-Year-Old Man Comes to the Emergency Department Due to 2