Table 1. Risk factors predisposing to CTEPH.

Clinical conditions predisposing to CTEPH

Large pulmonary emboli

Recurrent pulmonary emboli

Insufficient anticoagulation

Underlying autoimmune and haematological disorders

Ventriculo-atrial shunts

Infected pacemaker leads

Implantable chambers for intravenous chemotherapy (especially when infected)

Totally implantable central venous access systems

Splenectomy

Cancer and chronic myeloproliferative disorders

Thyroid replacement therapy

Biological risk factors predisposing to CTEPH

Non-O blood group

Presence of lupus anticoagulant/antiphospholipid antibodies*

*, interestingly, the classical hereditary thrombotic risk factors, e.g., protein C, protein S and antithrombin deficiencies and mutations of factor V and II are not more frequent in patients with CTEPH, compared with healthy controls and patients with pulmonary arterial hypertension. CTEPH, chronic thromboembolic pulmonary hypertension.