Echocardiographic signs of pulmonary hypertension in patients with newly recognized hypersensitivity pneumonitis, prevalence and clinical predictors

BACKGROUND: Hypersensitivity pneumonitis (HP) is the third, according to frequency, interstitial lung disease, with the estimated incidence rate of 1–2/100,000. In HP patients, the extensive inflammatory lesions encompassing both small airways and lung parenchyma, as well as subsequent development of lung fibrosis, may result in respiratory insufficiency and secondary pulmonary hypertension (PH). The aim of the present retrospective study was to assess the prevalence of echocardiographic signs of PH and its’ clinical predictors, in newly recognized HP patients. METHODS: Consecutive HP patients, recognized in single pulmonary unit between 2005 and 2017, in whom echocardiography was performed at diagnosis, entered the present study. HP diagnosis was verified in every patient according to current diagnostic recommendations. The results of high resolution computed tomography of the chest (HRCT) were re-evaluated by two independent radiologists, blinded to clinical data. Echocardiographic signs of PH were defined as pulmonary artery systolic pressure (PASP) exceeding 36 mmHg. Regression analysis was applied to calculate PH risk, and receiver operator characteristic curves (ROC) were plotted to investigate diagnostic utility of various parameters in PH prediction. RESULTS: PASP exceeding 36 mmHg was noted in 26 out of 70 patients (37%)—with equal frequency among patients with fibrotic and non-fibrotic HP. Significant predictors of PH on echocardiography were: partial oxygen tension in arterialized capillary blood (PaO2) <69 mmHg, lung transfer capacity for carbon monoxide (TLCO) <42% of predicted, six minutes walking test (6MWT) distance <455 meters, and 6MWT desaturation rate >8%. In case of TLCO <42% of predicted, probability of PH on echocardiography was increased by five-fold, in case of 6MWT desaturation rate >8%—by four fold. CONCLUSIONS: The best predictors of PASP >36 mmHg on echocardiography in HP patients at diagnosis were: TLCO <42% and 6MWT desaturation rate >8%. Neither the presence of lung fibrosis on HRCT, nor the duration of the disease or patients age, were helpful in PH prediction.