Emergency Department Diagnosis of Mitral Stenosis and Left Atrial Thrombus Using Bedside Ultrasonography

A 41-year-old woman with a medical history of a heart murmur and palpitations presented to the emergency department with a 3-day history of worsening shortness of breath, nausea, palpitations, and epigastric pain. She had a syncopal episode several hours prior to her emergency department visit. Her vital signs were normal except for her heart rate, as her electrocardiogram showed atrial fibrillation with a rapid ventricular rate of 165 beats/min. Her physical examination was normal except for an irregularly irregular heart rate and rhythm; her lungs were clear and her legs were neither tender nor swollen. Her urine pregnancy test was negative. A chest x-ray revealed cardiomegaly and mild pulmonary vascular congestion. Laboratory studies were normal except for a D-dimer of 12.5 (normal 0 to 0.54 μg/mL). A bedside ultrasound of the heart was performed (see Video Clips S1 and S2), which revealed a left atrial hyperechoic thrombus versus tumor mass in the parasternal long-axis view (Figure 1). Mitral stenosis was present in the parasternal short-axis view (Figure 2). The patient was given intravenous diltiazem for rate control and IV heparin therapy in the emergency department. She had a computed tomography angiogram of the chest performed that showed a left atrial thrombus or mass and left atrial appendage thrombus and no pulmonary embolism or deep venous thrombosis. Cardiology was consulted and a formal echocardiogram revealed severe mitral stenosis, severe left atrial enlargement, and a 2.8 × 2.9-cm mass attached to the mid left atrial wall. Cardiothoracic surgery was consulted and the patient was admitted and underwent mitral valve replacement (rheumatic mitral valve pathology), left atrial thrombus (pathology confirmed) removal, and a Maze procedure for atrial fibrillation. She was discharged home postoperative day 16 on warfarin.

Figure 1.  Parasternal long-axis view showing a left atrial hyperechoic thrombus versus tumor mass. LA = left atrium; LV = left ventricle; RV = right ventricle.

Figure 2.  Parasternal short-axis view of the heart showing mitral stenosis. LV = left ventricle; RV = right ventricle.

Mitral stenosis is associated with left atrial thrombosis in 17% of patients, and the addition of atrial fibrillation doubles the risk of left atrial thrombosis.¹ Patients with both mitral stenosis and atrial fibrillation who develop a left atrial thrombus are at risk for developing shortness of breath, syncope, and even cardiac arrest if the left atrial thrombus completely occludes the stenotic mitral valve producing obstructive shock.² Most intracardiac myxomas are located in the left atrium, attached to the intraatrial septum and, although rare, may be associated with mitral stenosis.³ The video clips illustrate how bedside cardiac ultrasonography can assist the emergency physician in the diagnosis of left atrial thrombus and mitral stenosis.