Introduction: Acute pulmonary embolism (PE) is a diagnostic and therapeutic emergency. Early antico-agulation or, if necessary, thrombolytic therapy, are mandatory in order to reduce morbidity and morta-lity. However, both diagnosis and treatment may be challenging, especially when the clinical presentation suggests an acute neurological event.

Methods: A 76-year old patient, without known car-diovascular disease, presented in the emergency de-partment with sudden onset of right sided paresis, dizziness, dyspnea and hypotension. Emergency bra-in CT showed left frontal hypodense area, and also signs of previous ischemic strokes. Blood tests showed elevated NT-proBNP and D-dimer levels, kidney fai-lure and hepatic cytolysis. ECG revealed minor right bundle branch block, negative T waves in V1V2 and S1Q3D3 pattern, suggesting increased right heart pre-ssure. Transthoracic echocardiography showed multi-ple thrombi in both atria, the largest one up to 30 mm in diameter, and atrial septal aneurysm with possible interatrial communication. Chest and abdominal CT revealed nearly occlusive endoluminal thrombus in both, main pulmonary arteries, extending to all lobar pulmonary arterie and in the distal segment of the right renal artery. At this point, the diagnosis was intracardi-ac thrombosis with pulmonary and paradoxical embo-lism, cerebral and renal.

Results: The PE severity index (PESI score) of 146, asso-ciated with significant atrial thrombosis and pulmonary hypertension were in favor of thrombolytic treatment. However, recent ischaemic stroke is an absolute contra-indication for thrombolysis, thus unfractionated hepa-rin and hemodynamic support were the only treatment options for the patient. Once the patient’s clinical status improved, the transesophageal echocardiography con-firmed the atrial septal defect with bidirectional shunt and a large thrombus in the right atrium passing throu-gh the defect during each cardiac cycle, creating a false impression of left atrial thrombosis. Breast cancer was diagnosed during patient’s hospitalization as the cause of her extensive thrombotic status.

Conclusions: We present a rare case of a patient pre-senting with signs of stroke and hypotension, due to massive right atrial thrombosis with pulmonary and paradoxical embolism due to a large atrial defect. An-ticoagulation only successfully led to patient complete recovery, with no signs of atrial thrombosis at dischar-ge.