Chronic thromboembolic pulmonary hypertension (CTEPH) is classified as Group 4 pulmonary hypertension and is the only form potentially curable with surgery. Pathogenesis involves incomplete resolution of acute pulmonary embolism with subsequent fibrotic organization of thromboemboli within proximal and distal pulmonary arteries, accompanied by progressive distal microvascular remodeling. Up to 3-4% of patients with acute pulmonary embolism develop CTEPH, with cumulative incidence increasing in the first 1-2 years post-event. Risk factors include unprovoked or recurrent VTE, large initial embolic burden, antiphospholipid syndrome, splenectomy, ventriculoatrial shunt, indwelling intravenous catheters, hypothyroidism, malignancy, and certain inflammatory conditions.
Patients typically present with progressive exertional dyspnea, fatigue, and exercise intolerance 3 months to several years after pulmonary embolism, often initially attributed to deconditioning or persistent post-PE symptoms. Advanced disease causes right heart failure with peripheral edema, hepatomegaly, and syncope. Echocardiography demonstrates pulmonary hypertension and right ventricular dysfunction. Ventilation-perfusion scintigraphy is the screening test of choice, showing segmental or larger mismatched perfusion defects with high sensitivity. Confirmation requires right heart catheterization (mean PAP greater than 25 mmHg with PCWP less than 15 mmHg) and pulmonary angiography or CT angiography to define lesion accessibility for surgery.
Treatment is guided by lesion location and surgical accessibility. Pulmonary endarterectomy (PEA) at experienced centers is curative in 95% of operable patients with proximal disease, achieving normalization of pulmonary pressures and survival exceeding 90% at 5 years. For inoperable distal disease (segmental and subsegmental), balloon pulmonary angioplasty (BPA) provides hemodynamic and symptomatic improvement comparable to PEA in selected centers. Medical therapy with riociguat (soluble guanylate cyclase stimulator) is approved for inoperable or persistent CTEPH after PEA, improving exercise capacity and pulmonary vascular resistance; treprostinil and macitentan are emerging options. Lifelong anticoagulation (vitamin K antagonist or direct oral anticoagulant) prevents recurrent thromboembolism. Multidisciplinary CTEPH expert centers integrating pulmonology, cardiothoracic surgery, interventional cardiology, and imaging optimize outcomes.