P0630 - A Young Man With Persistent Dyspnea: A Case of Chronic Thromboembolic Pulmonary Hypertension

A 22-year-old man presented with 6 weeks of increasing dyspnea on exertion and 20 pounds of weight loss over the preceding 6 months. His past medical history notable was for autism, hereditary spherocytosis (HS) and a mild pectus deformity. Given his sensitivity to loud noises, an evaluation in the emergency department (ED) was initially avoided in favor of a series of outpatient visits. Interval development of tachycardia and desaturation prompted referral to the ED. His exam was notable for euvolemia, and aside from tachycardia otherwise normal cardiopulmonary findings. CXR was unremarkable. ECG demonstrated sinus tachycardia, rightward axis, right ventricular hypertrophy and a right ventricular strain pattern with T wave inversions in II, III, aVF and V1-V4. A CT pulmonary angiogram demonstrated an enlarged right ventricle and multiple bilateral small subacute to chronic pulmonary emboli. The patient received anticoagulation for his submassive PE. A workup for provoking factors that extended into the outpatient setting found no malignancy or hypercoagulable state. Notably, this patient did not have a prior splenectomy for his HS, which would have otherwise been a thrombogenic risk factor. HS alone is not known to increase the risk of VTE.

Following discharge, the patient continued to have progressive fatigue and dyspnea. He and his parents returned to the ED 6 weeks later and he was found to have significant ambulatory desaturation. An echocardiogram showed a severely enlarged and hypokinetic right ventricle with evidence of pulmonary hypertension (pHTN). A ventilation/perfusion scan performed to assess for chronic thromboembolic pulmonary hypertension (CTEPH) demonstrated multiple filling defects and right heart catheterization confirmed precapillary pHTN, which taken together were consistent with CTEPH. He was not a candidate for surgical pulmonary thromboendarterectomy due to the distal nature of his clot burden. Balloon pulmonary angioplasty was similarly deferred and he was prescribed pharmacologic anti-pulmonary hypertensive therapy Initiation of riociguat, a soluble guanylyl cyclase activator recently FDA-approved for chronic inoperable CTEPH, and macitentan, an endothelin antagonist. This resulted in significant symptomatic improvement and in the outpatient setting a third agent—the prostanoid treprostinil—was added with further benefit.

This case represents a rare presentation of CTEPH in a young patient. This disease is more frequently encountered in adults but should be considered in younger patients who suffer from persistent dyspnea and activity limitation following the diagnosis and treatment of PE. The preferred and potentially curative therapy for patients with large, proximal pulmonary arterial thrombus burden is surgical pulmonary thromboendarterectomy. Those who are not candidates for surgery can receive catheter-based balloon pulmonary angioplasty or medical therapy. Currently only riociguat is FDA-approved for this indication but in practice many of the medical therapies for pulmonary arterial hypertension may be applied to CTEPH.