Cardiology Clinical Case / MCQS / Uworld for Usmle step 2 / case 6

 Cardiology Clinical Case  / MCQS / Uworld for Usmle step 2 / case 6 with answer and explanation and references and Educational objective

A 64-year-old man with a long history of uncontrolled hypertension comes to the emergency department with chest pain for the last 12 hours. He has never been hospitalized before. Electrocardiogram shows normal sinus rhythm with ST-segment elevation in the anterior leads. Coronary angiography shows complete occlusion of the proximal left anterior descending artery and no significant disease in the other coronary arteries. No intervention is performed and the patient is started on appropriate medical therapy. The next day he reports left leg pain. On examination, the left leg is cold with a mottled appearance. There is minimal swelling with absence of distal pulses. Vascular surgery is consulted. Which of the following should also be considered in this patient?

 

A.  Chest x-ray . B.  D-dimer levels . C.  Echocardiogram . D.  Venous Doppler study. E.  Ventilation-perfusion scan .

 

Answer : C

Explanation:

This patient most likely has acute limb ischemia from arterial occlusion, which is typically caused by cardiac emboli, thrombosis (eg, vascular stents, hypercoagulable states), or trauma. Major cardiac sources of arterial emboli include:

•      Left ventricular (LV) thrombus

•      Thrombus (usually left atrial) formation due to atrial fibrillation

•      Aortic atherosclerosis

Patients with large anterior ST-elevation Ml (STEMI) are at highest risk of LV thrombus and anteroapical aneurysm formation. Such patients often have an LV ejection fraction (EF) <40%. These patients are at high risk for systemic embolization (eg, stroke, peripheral arterial occlusion) and require immediate anticoagulation and vascular surgery evaluation. In addition, transthoracic echocardiogram with echo contrast must be performed to screen for LV thrombus.

 

(Choice A) Chest x-ray can be used for diagnosis of congestive heart failure or aortic dissection (ie, widened mediastinum). However, this patient has no symptoms of dyspnea or chest pain.

(Choice B and D) Heparin-induced thrombocytopenia (HIT) typically occurs 5-10 days after initiation of heparin therapy. Patients with HIT are prone to thrombosis (venous > arterial). Venous thrombosis typically presents with warmth, erythema, swelling, and tenderness. This patient's presentation and timing of symptoms suggest acute limb ischemia from arterial embolus; therefore, D-dimer levels and venous Doppler study are not required.

 

(Choice E) Ventilation-perfusion scan is used for diagnosis of pulmonary embolus, which typically presents with dyspnea, tachypnea, pleuritic chest pain, and signs or symptoms of lower-extremity deep venous thrombosis. This patient has no such symptoms.

 

Educational objective:

Acute limb ischemia after myocardial infarction suggests possible arterial embolus from left ventricular (LV) thrombus. Management includes immediate anticoagulation, vascular surgery consultation, and transthoracic echocardiogram to screen for LV thrombus and evaluate LV function.

 

References: 1. Left ventricular thrombus in patients with acute myocardial infarction: Case report and Caribbean focused update. New link : 1. Left ventricular thrombus in patients with acute myocardial infarction: Case report and Caribbean focused update.

 

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