CONGRESS ABSTRACT

Background: Patent foramen ovale (PFO) is a common congenital heart defect present in up to 34% of the population. While usually benign, it can facilitate right-to-left shunting, increasing the risk of paradoxical embolism in predisposed individuals. Although PFO is more commonly associated with cerebrovascular events, in rare instances, it can lead to coronary thromboembolism and acute myocardial infarction. Case Presentation: A 44-year-old man was admitted to the hospital with an inferior ST-segment elevation myocardial infarction (STEMI). Urgent coronary angiography revealed normal epicardial coronary arteries but showed slow flow in the distal left anterior descending artery, compatible with coronary thromboembolism. Cardiac MRI (Fig. 1) later confirmed subendocardial late gadolinium enhancement in the apical inferior wall of the left ventricle, indicating myocardial ischemia. A thoracic CT scan (Fig. 2) excluded pulmonary embolism but identified a large thrombus attached to the roof of the left atrium, entrapped in the PFO. Anticoagulation was promptly initiated, resulting in rapid resolution of the thrombus. Consistently, the transcranial Doppler (TCD) demonstrated a progressively increasing right-to-left shunt, initially absent but later severe (Fig. 3). The patient remained asymptomatic throughout the hospital stay. Two repeated lower extremity Doppler ultrasound showed no abnormalities. Abdominal ultrasound ruled out other potential embolic sources, including portal vein thrombosis. Screening tests for thrombophilia were within normal limits. As a definitive source of embolism could not be identified, in-situ thrombus formation at the PFO level, with subsequent coronary embolism, cannot be excluded. Given the causal role of the PFO and the risk of recurrent embolic events, elective PFO closure was scheduled. Conclusion: Paradoxical thromboembolism through a PFO is a rare but significant cause of STEMI in patients with normal coronary arteries. The embolic source may be difficult to identify, and in situ thrombus formation has been reported. An accurate diagnosis is crucial in these cases, as anticoagulant therapy and PFO closure are recommended.