Risk Factors for Chronic Thromboembolic Pulmonary Hypertension ? A Review

Chronic thromboembolic pulmonary hypertension (CTEPH) is a form of pulmonary hypertension caused by obstruction and vascular remodeling of pulmonary arteries following Pulmonary Embolism, which leads to increased pulmonary pressure and right ventricular failure. Several studies have reported that the incidence of the disease is between 0.1% and 9.1%. However, since many patients with CTEPH do not refer to have suffered an acute Pulmonary Embolism (PE), the true incidence of the disease is believed to be higher. Risk factors that predispose the development of CTEPH include: the initial size of thrombus and numerous associated host co morbidities. Homeostatic risk factors include: the level of plasma factor VIII and antiphospholipid antibodies or intrinsic abnormalities in fibrinogen. Co morbidities include: splenectomy, ventriculo-atrial shunts, infected pacemakers, blood groups other than 0, chronic inflammatory diseases such as osteomyelitis and inflammatory bowel disease, antiphospholipid antibodies, thyroid replacement therapy and a history of malignancy. The prognosis of this disease is poor, if left untreated. In symptomatic patients with surgically accessible CTEPH, the treatment of choice is pulmonary endarterectomy (PEA), but up to 40% of patients evaluated for PEA may be denied surgery for different reasons, including the presence of significant concomitant small-vessel disease. The aim of this article is to highlight the homeostatic factors and clinical conditions that increase the risk for CTEPH.