Recurrent Syncope Preceding Hemodynamic Deterioration in Acute Pulmonary Embolism with a Mobile Pulmonary Artery Thrombus: A Case Report

Background and Aims: Syncope is an uncommon presentation of acute pulmonary embolism (PE), frequently associated with right ventricular (RV) dysfunction and haemodynamic instability, though its independent prognostic significance remains uncertain. We report recurrent syncope preceding overt haemodynamic deterioration in acute PE with direct echocardiographic visualisation of a mobile pulmonary artery thrombus. Presentation of Case: A 60-year-old woman presented after two days of recurrent syncope. She was initially normotensive but tachycardic. Electrocardiography and continuous telemetry revealed no significant arrhythmia or high-grade conduction disturbance. D-dimer and cardiac troponin were elevated. Transthoracic echocardiography demonstrated RV dilatation, acute RV pressure overload, and a mobile thrombus at the main pulmonary artery bifurcation. Computed tomography pulmonary angiography confirmed extensive bilateral proximal PE. Despite anticoagulation, syncope recurred over the following 24 hours and was followed by persistent hypotension with systemic hypoperfusion. Systemic thrombolysis achieved rapid haemodynamic stabilisation and cessation of syncope. Repeat echocardiography at 48 hours showed the disappearance of the thrombus and improvement in RV function.