Virginia Research Day 2021

SUB-MASSIVE PULMONARY EMBOLUS TREATED WITH HALF-DOSE SYSTEMIC THROMBOLYSIS Stephen Canfield DO, MS; Ryan O’Connell DO Sovah Health Internal Medicine Residency Program, Danville, VA

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Background: Sub-massive pulmonary embolism (SMPE) is associated with significant right ventricular dysfunction which carries high morbidity and mortality. Compared with massive and non-massive pulmonary embolus (PE), no evidence-based medicine exists for optimal SMPE management. Chief Complaint & History : A 64-year-old African American female with a past medical history of unprovoked pulmonary embolus 5 years ago treated with rivaroxaban for 3 years presented with 1 week of worsening shortness of breath. Past Medical History: Unprovoked pulmonary embolism 5 years ago. Tubal ligation. Medications : No medications. Allergies: No known drug allergies. Family History : Sister had deep vein thrombosis (DVT) after knee replacement surgery. Pertinent Review of Systems : Diaphoresis, pleuritic chest pain, shortness of breath. Vital Signs: Temp 97.6, Blood pressure 132/90, pulse 130, respiratory rate 26, required 2L nasal cannula d/t oxygen desaturation in 80’s%. Social History: Sedentary office manager who is independent and performs all usual daily activities. No history of tobacco, alcohol, or illicit drug use. Pertinent Physical Findings: No acute distress. Normal S1 and S1, no gallop. Regular rhythm tachycardia. No respiratory distress, rhonchi, wheeze, jugular vein distention, pleural rub, or calf tenderness Pertinent Diagnostic Studies : WBC 8,360, Hgb 14.8, Troponin 1.44, BNP 59, D-dimer 7.32, PTT 28, PT/INR 1.2/13.8. No hypercoagulation studies were done.

Clinical Course (Cont):Following tPA , her PTT was 161 and fibrinogen was 155, so heparin drip resumed and continued for 36 hours. Symptoms and hypoxia resolved within 48 hours after tPA. She had no signs of symptoms of severe bleeding. Bilateral lower extremity ultrasound showed deep vein thromboses, so an inferior vena cava filter was placed. She was discharged home feeling well on rivaroxaban 15 mg BID for 21 days followed by 20 mg daily, indefinitely . Discussion: A sub-massive pulmonary embolus can cause significant right heart strain which can progress to obstructive shock. Current guidelines recommend treatment with anticoagulation unless with right heart strain which may be treated with full-dose thrombolysis. Studies have shown that patients with sub-massive pulmonary embolus and right heart strain treated with anticoagulation alone have increased morbidity and mortality compared to full-dose systemic thrombolysis combined with anticoagulation. Full-dose systemic thrombolysis rapidly reduces clot burden and right ventricular strain. However, full-dose thrombolysis carries the risk for severe bleeding and some practitioners are hesitant to use this dose. Alternative therapies for sub-massive pulmonary embolism are currently under investigation and include catheter-directed thrombolysis, low-dose systemic thrombolysis, and embolectomy. The lungs receive 100% of the cardiac output and research has shown that low-dose thrombolysis is effective at rapidly reducing clot burden and right heart strain. Low-dose thrombolysis carries an improved safety profile compared with full-dose thrombolysis. Conclusion: This patient presented with acute high risk, sub-massive pulmonary and was treated with half-dose tPA with rapid improvement of signs and symptoms and without evidence of bleeding. In this case , the reduced- dose tPA was found to be effective and safe. It was fortunate that our patient responded so well to this treatment.

ECG: Regular rhythm rate 128, prominent S-waves in lead I, Q-and T-waves in lead III (S1Q3T3 pattern) Arrow. CT Pulmonary Angiogram: Large saddle embolus in the left and right pulmonary arteries. Green Arrow

Echocardiogram: Ejection fraction >65% with severely dilated right ventricular (RV) and severely decreased RV function. .

Right Ventricle

Clinical Course: The patient was admitted to ICU with acute hypoxic respiratory failure secondary to acute high-risk, sub- massive saddle PE. She was begun on a heparin drip. Heparin drip was stopped, and she was given 10 mg tPA bolus followed by 40 mg tPA infusion over 2 hours .

References: 1. B Taylor, et al . (Jun 09, 2020. Overview of acute pulmonary embolism in adults Up-To-Date. 2.Victor F et al., Aug 31, 2020.Treatment, prognosis, and follow-up of acute pulmonary embolism in adults. Up-To-Date

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