Update on chronic thromboembolic pulmonary hypertension, a frequently undiagnosed condition.

Correspondence: Dr I. Lang, Professor of Vascular Biology, Department of Internal Medicine II, Division of Cardiology, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria E-mail: [email protected] Chronic thromboembolic pulmonary hypertension (CTEPH) results from an obstruction of the pulmonary vessels with organized blood clots. It is a common variant of pulmonary hypertension.1 There are about 2500 new cases in the United States each year,2 or a calculated prevalence of about 3 cases of CTEPH out of 100 cases of pulmonary embolism (approximately 20 per million). It is a long-term complication of symptomatic pulmonary embolism, with a cumulative incidence of 1% to 5% within 2 years after the embolic event.2-5 In addition, about 40% of the cases of CTEPH originate from asymptomatic venous thromboembolism.1,6