CT measures can refine PAH prognosis

By Eleanor McDermid, Senior medwireNews Reporter

Structural features identifiable on computed tomography (CT) pulmonary angiography can provide prognostic information for patients with pulmonary arterial hypertension (PAH), say UK researchers.

Smitha Rajaram (University of Sheffield) and co-workers studied 292 patients who were included in the ASPIRE registry between 2006 and 2010 and had undergone CT pulmonary angiography and high-resolution CT within 3 months of right heart catheterisation.

During follow-up lasting a maximum of 6 years, 112 of these patients died, and the researchers found that two features – inferior vena cava area and the presence of pleural effusion and/or septal lines – predicted death independently of pulmonary haemodynamics and World Health Organization functional class.

They note that both these features result from increased pressure in the right atrium, so are “not surprisingly associated with a poor outcome.” These findings on CT should therefore “alert the physician that the patient falls into a poor prognostic group prompting urgent referral for specialist assessment and treatment”, they say.

Other findings had diagnostic potential, such as ground glass opacities, which occurred in 41% of patients. The team says that “its presence should alert the physician to the possibility of PAH if the scan was performed for unexplained breathlessness” and should prompt them to look for other CT features suggestive of PAH.

The specific pattern of ground glass opacity was also suggestive of PAH subtype. Just over half of the patients with systemic sclerosis had a ground glass opacity that affected mainly the central part of the lung, with oesophageal dilation, whereas this was rare in other PAH subtypes.

By contrast, “a centrilobular ground glass pattern with a very large [pulmonary artery] and luminal calcification should suggest the possibility of an underlying congenital heart problem and prompt further investigation to confirm or refute these diagnoses”, writes the team in Thorax.

Some CT features, such as regurgitation of contrast into hepatic veins and enlargement of the right atrium, were frequent in all PAH subgroups. Others were specific to or more frequent in certain subtypes; for example, pulmonary artery calcification and mural thrombus occurred only in patients with congenital heart disease, and deviation of the interventricular septum towards the left ventricle was most common in patients with idiopathic PAH.

However, none of the differences observed between PAH subtypes were diagnostic, say the researchers.

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