The clot thickens: Diagnosing APS in the setting of multifocal thrombosis

Abstract Introduction Embolic stroke in young patients without traditional risk factors requires a broad differential, including structural heart disease, autoimmune thrombophilia, and hypercoagulable states. Antiphospholipid syndrome (APS) is a known prothrombotic condition. COVID-19 has also emerged as a driver of endothelial dysfunction and thrombosis. We present a case of a young woman with COVID-19 and heart failure symptoms who was found to have a left atrial thrombus, complicated by multisystem embolic phenomena. Case Discussion A 40-year-old woman with a past medical history of hypertension and anxiety presented with progressive fatigue, dyspnea, and lower extremity edema. Her vital signs at initial presentation were: BP 179/88 mmHg, heart rate of 45 bpm, O2 saturation of 94% on 3L NC. She appeared somnolent. Physical exam revealed JVD, bibasilar crackles, and lower extremity edema. Her labs revealed: WBC 24K, bicarbonate 19mmol/L, AST/ALT 359/202 U/L, bilirubin 2.4 mg/dL, CRP 10.8 mg/dL, TSH 7.19 µIU/mL (normal free T4), BNP 2300 pg/mL, troponin 1441 ng/L (no significant delta). The patient tested positive for COVID-19. Electrocardiogram (EKG) showed sinus rhythm with 2:1 AV block. Chest x-ray revealed bilateral opacities. Transthoracic Echocardiogram (TTE) showed a mobile echogenic mass in the left atrium. She was admitted to the ICU and started on dexamethasone, antibiotics, diuretics, and therapeutic heparin. On hospital day one, she developed dysarthria and encephalopathy. MRI brain revealed embolic infarcts. Transesophageal Echo (TEE) confirmed a mobile left atrial mass concerning for thrombus vs. myxoma. A left heart catheterization showed complete mid-circumflex occlusion with preserved left ventricular function. The patient underwent surgical resection of the mass with left atrial appendage exclusion. Pathology confirmed thrombus. Her course was complicated by seizures and encephalopathy which resolved. She also experienced a gastrointestinal (GI) hemorrhage with which a CT angiogram abdomen and pelvis also revealed a renal artery thrombosis. Temporary pacing was required for AV block that later resolved. Given persistent thrombosis and remaining work up being negative, a hypercoagulability profile was ordered. The workup revealed elevated anticardiolipin antibodies, leading to a likely diagnosis of antiphospholipid syndrome. These labs were to be repeated in the outpatient setting to further establish the diagnosis. She was discharged on warfarin with appropriate follow-up. Discussion This case illustrates the complexity of diagnosing and managing embolic phenomena in a young patient with overlapping structural, infectious, and autoimmune conditions. Antiphospholipid syndrome (APS) is an autoimmune condition characterized by the presence of antiphospholipid antibodies, lupus anticoagulant, anticardiolipin, anti-β2 gylcoprotein 1 antibodies, and a predisposition to thrombosis. It is often underdiagnosed, particularly in younger patients without obvious risk factors. In this patient, APS likely contributed to both her intra-atrial thrombus and multiple arterial occlusions. COVID-19 also further potentiated thrombus formation in a patient with underlying APS. A diagnosis of Catastrophic APS (CAPS) was considered; however, the patient did not meet criteria for definite or probable CAPS. Conclusion: This case highlights the complex interplay of autoimmune, cardiac, and infectious triggers of thrombosis. COVID-19 also potentiated thrombus formation in a patient with underlying APS. Early echocardiography, surgical intervention, and anticoagulation were key to survival.