Advances in understanding the pathogenesis of chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) comprises organizing thrombotic obstructions in the pulmonary arteries. While roughly 40% of CTEPH cases are not preceded by a venous thromboembolic event, 0.1-5.1% of acute pulmonary thromboemboli evolve into organized obstructions of the pulmonary artery. In patients with predominantly proximal disease, surgical pulmonary endarterectomy provides a potential cure of the disease. For years, the scientific debate of CTEPH was mainly focused around its thromboembolic nature because of striking dissimilarities to classical venous thromboembolism, for example, the lack of risk factors for venous thrombosis, the lack of clinically apparent pulmonary embolism in many patients, the difficulty to reproduce the disease in animal models of thrombosis, and the nature of the pulmonary vascular obstructions that are dissociated from the degree of hemodynamic compromise. Recent studies have confirmed an association between venous thromboembolism and the evolution of CTEPH, and have shed light on disease-modifying conditions.