A 39-year-old woman with a history of smoking hookah daily for one year and does not drink alcohol, had a history of Deep Venous Thrombosis (DVT) in the left lower leg for 13 years, which started during the first trimester of her first pregnancy. She was treated with low molecular weight heparin, and was diagnosed with a Covid-19 infection 2 years ago without the need for hospital admission. She had no history of miscarriage, diabetes, or hypertension. The patient came to the emergency department at our hospital suffering from a 6-month history of fatigue, and dyspnea (NYHA: class II-III) accompanied by severe compressing chest pain behind the sternum which spreads to the left arm and between the shoulder blades, which lasted for 30 minutes, and went away gradually. During the last two months, she complained of two episodes of syncope occurring for a period of 2-3 minutes, preceded by palpitations and blurred vision. Physical examination showed a fixed split in the first heart sound S1, which was best heard at the tricuspid valve area. A 12-lead electrocardiogram showed sinus rhythm and a normal axis, without abnormal electrical findings. Chest radiography revealed a normal-sized heart with no abnormalities noted in the heart and lungs. Emergency causes of chest pain and dyspnea were excluded using ECG, laboratory blood tests, and an emergency echocardiogram. However, the presence of a large mass in the right cavity of the heart was disocvered. The patient was then admitted to the CCU for follow-up and continued cardiac investigation to determine and treat the causative disease. The patient was treated with aspirin 81 mg and unfractionated heparin (UFH) (with APTT ranging between 70-90 sec) while bridging to warfarin with an INR that ranged between (2.5-3).

Transesophageal Echocardiography (TEE) was performed on the third day of admission to the CCU. A TEE showed a hyperechoic lobulated mass starting from the middle of the inferior vena cava and extending to the right atrium, prolapsing through the tricuspid valve towards the right ventricle. The mass was also mobile and measured 5.13×1.53 cm. All cardiac chambers were normal in shape and size, had good motility in all cardiac walls, and had good systolic function (Figure 1). Doppler echography of the lower limbs showed normal findings, with no signs of deep vein thrombosis or arterial thrombosis.

The routine blood testing revealed: WBC:6600u/l, HGB:9.8 g/dl, PLT:215000u/l, creatinine:1 mg/dl, urea:26 mg/dl, INR:1.1, PT:13s, ALT:39u/l, AST:42u/l, TSH:1.4 mIU/ml, CRP:2.2 mg/dl, cholesterol:205 mg/dl, TG:230 mg/dl. Moreover, Wright test, Widal test, HBV and HCV tested negative.

MSCT was performed on the third day to rule out the presence of a pulmonary embolism and showed embolic filling defects in the branches of the left pulmonary arterioles. The pulmonary trunk and the left and right pulmonary arteries were normal. Thrombotic filling defects were observed in the inferior vena cava pathway (Figure 2). Cardiac magnetic resonance imaging was done on the sixth day of admission to determine the likely histological structure of the mass, and showed the presence of a mobile thrombotic mass measuring 20 × 35 mm hanging from the atrium towards the ventricle through the tricuspid valve, consistent with an embolus (post-thrombosis of the inferior vena cava). The pulmonary trunk and parenchyma were normal (Figure 3). Cardiac coronary angiography results were also normal (Figure 4).

Laboratory immunological tests were negative for homocysteine, protein S and C activities, factor V Leiden, antithrombin III deficiency, and normal fibrinogen. Antiphospholipid IgG antibodies, Antiphospholipid IgM antibodies, Anticardiolipin IgG antibodies, Anticardiolipin IgM antibodies, lupus anticoagulant, and Anti DNA (ds) also tested negative. In contrast, ANA-HEP-2 tested positive. Thus, the patient was diagnosed with seronegative APLS based on the highly suggestive clinical manifestations. Surgical intervention was discussed with the cardiac surgery team after confirming the diagnosis with the rheumatology team, but the patient refused surgical intervention despite being informed of the seriousness of the condition. We decided to complete the treatment with warfarin, and the patient remained in the CCU for three weeks, during which time the symptoms completely resolved. The mass diameters started to decrease after the fourth week of treatment, and diminished to about 2.0x2.6 cm. The patient was discharged on lifelong warfarin during home treatment with continuous follow-up.