A giant and double-walled left atrial ball thrombus complicating a mitral stenosis: case report-a truck tire into the heart

Background: High thromboembolic risk associated with rheumatic mitral stenosis has been well established, especially in concomitant atrial fibrillation; however, the presence of left atrium ball thrombus is an uncommon finding.

Case summary: A 75-year-old woman with a history of mild rheumatic mitral stenosis was admitted to Emergency Department with cardiogenic shock and high ventricular rate atrial fibrillation. Emergency electrical cardioversion was performed-before trans-oesophageal echocardiography (TOE)-due to haemodynamic deterioration which restored sinus rhythm.Transthoracic echocardiography (TTE) revealed severe reduction of left ventricular ejection fraction (LVEF: 15%), severe rheumatic mitral stenosis and a large, perfectly rounded mass, situated at the ostium of left upper pulmonary vein. Due to the persistence of haemodynamic instability and acute pulmonary oedema the patient was intubated and mechanically ventilated and treated with intravenous administration of inotropes and high doses of diuretics. During the stay in Intensive Care Unit, a TOE confirmed a spherical and double-walled mass suggesting a working diagnosis of left atrial ball thrombus (LABT). The case was discussed in Heart Team and considering the poor haemodynamic status in the contest of refractory cardiogenic shock with evidence of multi-organ failure, emergency surgical thrombectomy and mitral valve replacement was deemed prohibitive. Patient developed cardiac arrest and emergency TTE showed left atrial mass engaged into the mitral valve totally obstructing the left ventricle inflow tract. The autopsy and histologic examination confirmed the thrombotic nature of the mass.

Discussion: A free-floating ball thrombus in the left atrium is an unusual occurrence in rheumatic mitral stenosis and it may cause fatal systemic embolization or acute left ventricular inflow obstruction, resulting in syncope, pulmonary congestion, and sudden cardiac death. When possible, emergency surgical thrombectomy and mitral valve replacement can be life-saving.