Abstract Body (Do not enter title and authors here): Introduction:
Multisystem thromboembolism is a rare, life-threatening condition that requires rapid identification and intervention. In the presence of a right-to-left shunt, paradoxical embolism can lead to simultaneous infarctions across multiple organ systems. This case illustrates the importance of considering paradoxical embolism in patients presenting with embolic events affecting multiple vascular territories.
Case Presentation:
A 63-year-old male with a history of non-small cell lung cancer, ambulatory dysfunction, type 2 diabetes, and hypertension presented with dyspnea and abdominal discomfort. In the emergency department, he developed acute chest pain and ECG changes concerning for posterior ST-elevation myocardial infarction (STEMI). While awaiting cardiac catheterization, he experienced a pulseless electrical activity (PEA) arrest with return of spontaneous circulation within 4 minutes.
CT angiography revealed bilateral pulmonary emboli (PE) with right heart strain. Emergent coronary angiography showed occlusion of the left circumflex artery, which was successfully stented. Pulmonary thrombectomy was performed the following morning with effective clot extraction. Despite aggressive management, the patient developed progressive renal and hepatic failure with worsening lactic acidosis. Abdominal CT revealed extensive bowel ischemia due to acute mesenteric embolism. Transthoracic echocardiography with bubble study confirmed the presence of a patent foramen ovale with right-to-left shunting, consistent with paradoxical embolism.
Outcome:
Given the extent of bowel necrosis and multiorgan failure, surgical intervention was not pursued, and care was transitioned to comfort measures.

Conclusion:
This case underscores the importance of considering paradoxical emboli in patients with embolic involvement of multiple organs. In cases of persistent lactic acidosis despite targeted intervention, clinicians should maintain a high index of suspicion for occult embolic sources and intracardiac shunting. Early recognition and comprehensive diagnostic workupmay improve clinical outcomes.