RV Thrombus- a Hidden Iceberg Behind Sudden Deterioration in a COVID-19 Patient

Patients with COVID-19 pneumonia are at higher risk of developing thromboembolic events including pulmonary embolism, deep vein thrombosis, ischemic stroke, and myocardial infarction. We report a case of a patient who developed a right sided ventricular thrombus despite being on therapeutic anticoagulation. A 49-year-old man with no past medical history was admitted to the hospital due to COVID-19 pneumonia. He was started on therapeutic Enoxaparin due to D-dimer of 17710ng/ml. Lower extremity duplex was negative for deep vein thrombosis. Patient was enrolled in Sarilumab trial and received the intervention on day 3 and 4 of admission. Initially patient's oxygen requirements decreased, and D-dimer levels trended down. But on day 11, patient was hypotensive, hypoxic to 84% on 5L NC. Differentials included-Pulmonary embolism, Progression of COIVD-19 pneumonia, ARDS, superimposed bacterial pneumonia. Further workup included repeat chest x-ray which showed resolving bilateral infiltrates. D-dimer was 4388ng/ml. A bedside echocardiogram showed right ventricular dilation and a large mobile echo-dense mass measuring 12mm∗11mm compatible with a Right Ventricular thrombus. CT chest revealed right lower lobe pulmonary embolus and evidence of right heart strain. Patient was transferred to the ICU. Enoxaparin was stopped, a bolus of tissue plasminogen activator (tPA) 50mg was administered over 2 hours followed by a 1mg/hr infusion. Heparin drip with a PTT goal of 30-50 seconds was administered simultaneously for 24 hours. Fibrinogen levels were checked every 6 hours to ensure levels remained above 150 mg/dl. After 24 hours, echocardiogram showed persistent RV mobile thrombus and McConnell's sign. The above infusion protocol was repeated for 24 hours. After tPA infusion patient O2 requirements down trended from nonrebreather 15L to NC 5L. Repeat echo showed resolution of RV thrombus. Repeat CTPE had no new filling defects. There were no bleeding events. Patient was transitioned to apixaban and transferred stable to the floors. Patients with COVID-19 are at higher risk of developing hypercoagulability and it is associated with a worse prognosis. Bedside echocardiogram is a rapid accessible test that can be used in acute decompensating patients. Consecutive doses of tPA appear to be a safe and effective option for the treatment of right heart thrombus. Infusion endpoint for such patients include significant bleeding, drop in hemoglobin by 2 g/dl, fibrinogen <150mg/dl, and/or thrombus resolution on echocardiogram. Our patient showed improvement after tPA infusion perhaps by the thrombus lysis or lysis of the microthromboemboli and fibrin deposits of the pulmonary microvasculature.