New interventions to treat chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) can be defined as a type of precapillary pulmonary hypertension (PH) resulting from incomplete resolution of pulmonary embolism. Symptoms are exertional breathlessness and most patients come to a cardiologist's attention with a dilated right heart on echocardiography. Patients with suspected CTEPH should be referred for evaluation to a PH specialist centre to confirm the diagnosis. There are now three treatment options available, dependent on the anatomical level of the obstruction: pulmonary endarterectomy surgery, balloon pulmonary angioplasty and pulmonary arterial hypertension (PAH)-targeted drugs. All reduce pulmonary artery pressure and vascular resistance. Current guidelines recommend surgery as the definitive treatment in technically operable patients. The operation involves deep hypothermic circulatory arrest, but the in-hospital mortality is <5% and the 3-year survival is 90%. Large case series have demonstrated dramatic improvement in haemodynamic parameters with significant symptomatic and prognostic benefits. Balloon pulmonary angioplasty is the newest treatment that has been refined by Japanese cardiologists over the last 5 years. This technique is designed to target more distal subsegmental lesions in inoperable patients and in experienced centres has been shown to deliver equivalent haemodynamic improvement to surgery with low complication rates, but longer term outcome is still under evaluation. A recent randomised controlled trial has demonstrated a reduction in vascular resistance and increase in walk test distance with the PAH-targeted drug Riociguat in patients with inoperable CTEPH, and this drug is now licensed for these patients. It is likely that some patients will benefit from combinations of treatments.