A 64-year-old man with a long history of uncontrolled hypertension is brought to the emergency department due to chest pain for the last 8 hours. ECG reveals normal sinus rhythm with ST-segment elevation in the anterior leads. Percutaneous coronary intervention, performed via right femoral artery access, demonstrates complete occlusion of the proximal left anterior descending artery. Stenting is performed, and appropriate medical therapy is initiated. Six days later, the patient develops sudden onset of severe left leg pain. On examination, the left lower leg is cold and mottled in appearance, without swelling. The femoral pulses are palpable and symmetric; the pedal pulses are present on the right and absent on the left. Vascular surgery is consulted. Which of the following should also be considered in this patient?

Question

A 64-year-old man with a long history of uncontrolled hypertension is brought to the emergency department due to chest pain for the last 8 hours.  ECG reveals normal sinus rhythm with ST-segment elevation in the anterior leads.  Percutaneous coronary intervention, performed via right femoral artery access, demonstrates complete occlusion of the proximal left anterior descending artery.  Stenting is performed, and appropriate medical therapy is initiated.  Six days later, the patient develops sudden onset of severe left leg pain.  On examination, the left lower leg is cold and mottled in appearance, without swelling.  The femoral pulses are palpable and symmetric; the pedal pulses are present on the right and absent on the left.  Vascular surgery is consulted.  Which of the following should also be considered in this patient?

Quizplus · Accepted Answer

This patient with sudden onset of severe left leg pain and signs of arterial occlusion (eg, cold, mottled leg lacking pedal pulses) has acute limb ischemia (ALI). Although ALI is often due to thrombosis (eg, plaque), it can also be caused by embolism (eg, thrombus). Given this patient's recent anterior ST-segment elevation myocardial infarction (STEMI), his ALI is most likely due to embolization of a left ventricular (LV) mural thrombus. Patients with a large anterior STEMI from occlusion of the proximal left anterior descending artery are at highest risk for LV aneurysm formation, especially when reperfusion therapy is unfeasible or delayed (eg, treatment initiated after 8 hr of ischemia in this patient). When an LV aneurysm forms, the infarcted muscle fails to contract (or even balloons outward) during systole and is associated with a low ejection fraction and stasis of adjacent blood. This may lead to formation of an LV thrombus that can embolize, causing stroke or ALI, as in this patient. In addition to emergency treatment of ALI (eg, heparin infusion, vascular surgery consultation), this patient should undergo transthoracic echocardiography (TTE) with contrast to assess for an LV aneurysm and/or residual thrombus. The presence of either finding may impact the duration of anticoagulation. (Choice A) Ongoing or recent intravascular coagulation and fibrinolysis can cause elevated D-dimer, a product of fibrin degradation. Although the D-dimer level might be elevated in this patient with LV thrombus, the test is nonspecific and can be elevated from several other conditions (eg, malignancy, pulmonary embolism, infection, inflammation). (Choice C) Heparin-induced thrombocytopenia (HIT) typically occurs 5-10 days after initiation of heparin therapy. Patients with HIT are prone to thrombosis, and venous is more common than arterial thrombosis. However, lower extremity venous thrombosis, which can be detected with venous Doppler study, typically causes swelling and/or warmth. (Choice D) Femoral arterial cannulation during percutaneous coronary intervention can be complicated by acute thrombosis or pseudoaneurysm (with subsequent thrombosis), which may be detected on groin ultrasound. However, the resulting ALI would affect the ipsilateral lower leg (ie, right leg in this patient), and the femoral pulse would be abnormal. (Choice E) Ventilation-perfusion scan may be used to diagnose pulmonary embolus, which typically presents with dyspnea, tachypnea, pleuritic chest pain, and symptoms/signs of lower extremity deep venous thrombosis. This patient has no such symptoms. Educational objective: Acute limb ischemia after myocardial infarction suggests embolization of a left ventricular (LV) thrombus. Transthoracic echocardiography should be performed to screen for LV aneurysm and/or residual LV thrombus. References: Predictors and prognosis of left ventricular thrombus in post-myocardial infarction patients with left ventricular dysfunction after percutaneous coronary intervention. (http://www.ncbi.nlm.nih.gov/pubmed/30233865) In-hospital left ventricular thrombus following ST-elevation myocardial infarction. (http://www.ncbi.nlm.nih.gov/pubmed/31371119)

A 64-Year-Old Man with a Long History of Uncontrolled Hypertension