B64-47 Silent Obstruction: Chronic Thromboembolic Pulmonary Hypertension Beyond Imaging

Abstract Introduction Chronic thromboembolic pulmonary hypertension (CTEPH) is a complication of pulmonary embolism (PE) in about 1–3.8% of cases within the first two years following a PE 1. Diagnosis can remain clinically challenging, particularly in patients with complex cardiovascular and thromboembolic histories. Described is a case of CTEPH diagnosis despite a negative V/Q scan. Case Presentation A 44-year-old woman with past medical history of asthma, hypertension, obesity, uterine fibroids, prior STEMI, and pulmonary embolism in 2021 (status post PFO closure and loop recorder placement in 2023) presented with worsening dyspnea and cough. She had recurrent PE in February 2025 and was restarted on Apixaban. On presentation, she was tachycardic (HR 110s) with stable blood pressure and oxygen saturation 95% on 5L nasal cannula. Laboratory studies showed leukocytosis (WBC 16.7), BNP 152, and INR 1.6. Computed tomography angiography (CTA) was negative for PE; however, transthoracic echocardiogram demonstrated a right atrial (RA) thrombus and severe pulmonary hypertension. V/Q scan showed low probability for CTEPH. Right heart catheterization confirmed precapillary pulmonary hypertension (mean PAP 45 mmHg, PCWP 6 mmHg, PVR 780 Wood Units) consistent with chronic thromboembolic pulmonary hypertension (WHO Group IV). Discussion The American College of Cardiology (ACC) recommends that a V/Q scan be performed as the initial imaging modality when evaluating suspected CTEPH, as it remains more sensitive than CTA for detecting chronic thromboembolic disease 2. This patient had a complicated thromboembolic history including recurrent PEs and a newly diagnosed RA thrombus. The V/Q scan was negative for CTEPH. Few studies discuss patients who have had negative V/Q scans but were found to have CTEPH 3. Echocardiogram showed severe pulmonary hypertension, confirmed with right heart catheterization. A possible explanation for the negative V/Q scan is that since the patient was on anticoagulation for several months, this may have led to partial resolution of old embolic lesions, creating a normal V/Q scan despite obstruction. Furthermore, if thrombotic material is in distal arterioles, these would not appear as perfusion defects on the V/Q scan 4. Conclusion This case underscores the importance of maintaining a high index of suspicion for CTEPH in patients with a negative V/Q scan, especially with thromboembolic events, shortness of breath, negative autoimmune and hypercoagulable workup, or unexplained pulmonary hypertension. This abstract is funded by: None