Chest radiography is very accurate for predicting pulmonary hypertension (PH), report researchers.
The team, led by Massimo Miniati (Università di Firenze, Italy), examined chest radiographs of 108 patients with suspected PH, 57 with left heart failure, 197 with chronic obstructive pulmonary disease and 200 control patients with none of these disorders.
“We felt inappropriate to rule in a radiologic diagnosis of PH only on the basis of a prominent main pulmonary artery,” the researchers write in Thrombosis Research.
For this reason, they required the presence of at least one additional finding for a PH diagnosis: isolated enlargement of the right ventricle; a right descending pulmonary artery diameter greater than 16 mm; or pruning of peripheral pulmonary vessels.
“By adopting these criteria, chest radiography yielded high diagnostic accuracy for PH,” they report.
A total of 82 patients had PH confirmed on right heart catheterisation (RHC). The percentage of these cases identified by chest radiography by four raters ranged from 95.1% to 98.8%, to give a weighted sensitivity of 96.9%.
“A chest radiograph strongly suggestive of PH makes the diagnosis very likely and should prompt confirmatory tests, including RHC,” say the researchers. “Conversely, if the chest radiograph does not meet the criteria for PH, it is unlikely that the disease be present.”
Six patients with confirmed PH were rated as negative on chest radiography by at least one rater. These patients had generally mild elevations of mean pulmonary artery pressure, ranging from 26 to 35 mmHg, compared with an average of 41 mmHg among the other PH patients. And four of the false-negative cases had coexisting lung fibrosis.
The team notes, however, that “even computed tomography is unable to reliably predict PH in the presence of diffuse interstitial lung disease”.
Among all patients, the specificity of chest radiography was 99.8%, and among 165 who underwent RHC (including the suspected PH cases) it was 99.1%.
Miniati et al note that the clinical pre-test probability of PH is often intermediate because of the nonspecific presentation signs and symptoms. However, a pre-test probability of 50% changes to 98% in the event of a positive chest radiography result and 3% after a negative result. Therefore “the simple taking of the chest radiograph may aid clinicians in decision making”.
They add: “Chest radiography is still ubiquitous in clinical practice, and will likely remain so for quite some time for it is inexpensive and minimally invasive in terms of radiation exposure.”
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