APCU25MPB7 Caught in transit: a case of submassive PE, right heart thrombus, and stroke after thrombolysis

Introduction Clot-in-transit (CIT) is a rare but critical manifestation of venous thromboembolism, carrying an immediate risk of embolization into the pulmonary circulation and high morbidity and mortality. We report a case of CIT with pulmonary embolism (PE) successfully treated with tissue plasminogen activator (tPA).Case Presentation A 33-year-old man with young-onset hypertension presented with 2 days of progressive dyspnea and preceding 2 months of heart failure symptoms. He was tachycardic, hypoxic (SpO&noentity8322; 90% on room air), and hypertensive (141/100 mmHg) with raised JVP but no extremity oedema or signs of deep venous thrombosis. Arterial blood gas showed type 1 respiratory failure. Troponin I was normal. ECG revealed sinus tachycardia with T inversion in lead III; chest X-ray showed cardiomegaly. Transthoracic echocardiography demonstrated preserved EF (58%), dilated right ventricle, moderate tricuspid regurgitation, and a large mobile right atrial thrombus. While awaiting CT pulmonary angiography (CTPA), he developed two episodes of generalized tonic–clonic activity with incontinence, attributed to convulsive syncope. PE protocol CTPA revealed extensive bilateral main, segmental, and subsegmental pulmonary artery thrombi with right atrial thrombus and right heart dilatation. Anticoagulation with subcutaneous fondaparinux was initiated. Pulmonary Embolism Severity Index (PESI) score was 83; simplified PESI was 1. He was categorized as intermediate–low risk but, given his extensive PE, hypoxia and RV strain, he received intravenous alteplase. One hour post-thrombolysis, his GCS dropped to E4V4M5 (NIHSS 3). CT brain showed left MCA infarct. CT angiography/venography next day revealed no arterial or venous occlusion, consistent with resolving infarct. He was transitioned to therapeutic enoxaparin and later discharged on oral anticoagulation with full recovery.Discussion CIT in PE triples mortality risk compared to PE alone and independently predicts poorer outcomes. No definitive guidelines exist; management options include anticoagulation, thrombolysis, or surgical embolectomy. A meta-analysis reported mortality of 11% with thrombolysis, 24% with embolectomy, and 29% with anticoagulation alone, supporting thrombolysis as potentially favourable in select cases.Conclusion Early recognition and prompt treatment of CIT are crucial. In this case, systemic thrombolysis was effective despite the patient being in an intermediate-high-risk category, where benefits are less established.