A Moving Threat: Fatal Course of a Clot in Transit

Document Type

Conference Proceeding

Publication Date

5-2026

Publication Title

American Journal of Respiratory and Critical Care Medicine

Abstract

Introduction: Clot in transit (CIT) denotes a thrombus temporarily lodged in the right heart before entering the pulmonary circulation. These thrombi, often freely mobile within the right atrium, ventricle, superior or inferior vena cava (IVC), carry a high risk of dislodgement and fatal pulmonary embolism (PE). Case: A 72-year-old woman with chronic obstructive pulmonary disease on home oxygen and atrial fibrillation post-ablation (not on anticoagulation) was admitted for fever, dyspnea, and hypoxemia. She required emergent intubation for refractory hypoxemia and received fluids, broad-spectrum antibiotics, and vasopressors for persistent hypotension. Laboratory studies showed lactic acid rising from 3.7 to 17 mmol/L, D-dimer >10,000 ng/mL, BNP 358 pg/mL, and positive COVID-19 PCR. Point-of-care ultrasound (POCUS) revealed atypical septal motion, an ejection fraction of ~30%, and a mobile thrombus in the IVC. Given instability, further imaging was deferred, and intravenous heparin was initiated. Despite intensive care and continuous renal replacement therapy, she developed worsening acidemia, anuria, and refractory shock. The patient ’s family opted against further escalation. The patient suffered cardiac arrest and died within 24 hours of admission. Discussion: Three major types of right heart thrombus (RHT) can be distinguished on echocardiography: Type A (most common) is serpiginous and freely mobile within the cardiac chambers. Type B originates from the atrium or ventricles, is ovoid-shaped, and firmly attached to the chamber wall. Type C is highly mobile, such as cardiac myxomas. CIT is type A RHT, frequently associated with acute PE. It is a catastrophic end of the deep venous thrombosis-PE spectrum, occurring in 2-5% of PE cases and up to 18% of high-risk PE. Compared with PE alone, CIT confers a worse prognosis: untreated mortality has been documented to approach 80-100%. One meta-analysis of 492 patients with CIT + PE reported a mortality of 35% for anticoagulation alone, 31% for surgical thrombectomy, 20% for catheter-based thrombectomy, and 12% for systemic thrombolysis. Given the potential for thrombus migration from the right heart into the pulmonary vasculature, prompt recognition via POCUS or transthoracic echocardiography (TEE) is needed. TEE should be used early when available to localize thrombus in the pulmonary artery or lodged in a patent foramen ovale. As there are no consensus guidelines, optimal management remains uncertain. Management should be individualized based on patient comorbidities, hemodynamics, thrombus morphology (mobility, attachment, right-heart location), and institutional capacities. A multidisciplinary team (PERT) approach with readiness for escalation in the setting of clinical deterioration or mobile/valve-prolapsing thrombus is needed.

Volume

212

Issue

S1

First Page

S2437

Comments

American Thoracic Society International Conference, May 15-20, 2026, Orlando, FL

Last Page

A2437

DOI

10.1093/ajrccm/aamag162.3233

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