Predictors of pulmonary hypertension in patients with hypersensitivity pneumonitis

Abstract

Background Hypersensitivity pneumonitis (HP) is an immunologically induced inflammation of the lung parenchyma that occurs in susceptible individuals in response to a variety of antigens. Repeated exposures to the causative antigens lead to chronic HP. The condition could be complicated with pulmonary hypertension (PH). Methodology 60 patients with established diagnosis of HP were included, clinical examination, high resolution computed tomography (HRCT) of chest, arterial blood gases, six minute walking test (6MWT), desaturation index, spirometry, echocardiography were performed to all patients and right heart catheter was done for patients with high echo probability of PH. Results The mean age of patients was 41.67 ± 13.4 years with female predominance 83.3% of patients had history of raising birds. 71.7% of cases suffered from resting hypoxia with oxygen saturation 89 ± 11% with desaturation index 9% ± 8%, Echo probability of PH ranged from low to high 71.67, 21.67 and 6.67% respectively, mean pulmonary artery systolic pressure was 63.65 (18.48) mmHg. PH was diagnosed in 17 (28.33%) patients. HP with PH patients were significantly more symptomatic with predominant fibrotic pattern in HRCT chest P < 0.001, 82% of them had hypoxia P < 0.001 with significant desaturation after 6MWT P = 0.001. Predictors of PH in study group were fibrotic pattern in HRCT chest and hypoxia OR = 62.22, P < 0.001; 49.2, P < 0.001 respectively. Conclusion PH was prevalent in 28.33% of patients with HP, predictors of development of PH were fibrotic pattern in HRCT chest and hypoxia. Trial registration: Retrospectively registered, registration number is NCT05458635, date of registration 07/12/2022.

Vasoreactive pulmonary artery hypertension in non-fibrotic hypersensitive pneumonitis

“…The mechanism of PH and vasoreactivity is heterogeneous in fibrotic hypersensitivity pneumonitis. Vascular remodelling and arterial stiffening secondary to hypoxia-mediated vasoconstriction, endothelial dysfunction, and progressive fibrosis act as the main drivers of PH in fibrotic HSP 8. Elnady et al found fibrosis on CT scans to have a 49 times higher risk of developing PH than non-fibrotic HSP 8.…”

“…Vascular remodelling and arterial stiffening secondary to hypoxia-mediated vasoconstriction, endothelial dysfunction, and progressive fibrosis act as the main drivers of PH in fibrotic HSP 8. Elnady et al found fibrosis on CT scans to have a 49 times higher risk of developing PH than non-fibrotic HSP 8. Vasoreactivity in non-fibrotic hypersensitivity pneumonitis has not yet been described, and the mechanism is unclear.…”

Predictors of Pulmonary Hypertension and Right Ventricular Dysfunction in Patients with Hypersensitivity Pneumonitis

“…Similar results were demonstrated by Dybowska et al, who detected PH in 26 of 70 patients with HP (37.0%) [ 8 ]. In a recent study by Elnady et al, the frequency of PH was slightly lower (28.3%) [ 9 ]. In another study, PH was detected in 19.0% of patients with HP using sPAP 50 mm Hg as TTE diagnostic threshold [ 23 ].…”

“…However, the UIP pattern in HP patients, according to our results, was not a significant predictor of PH. In a recently published study by Elnady et al, patients with HP with and without PH also differed in the predominance of fibrosis according to HRCT [ 9 ]. Similarly, Walscher et al showed an association between the diagnosis of PH and the UIP pattern in patients with HP [ 15 ].…”

“…At the same time, PH can also be detected in patients with IPF without hypoxemia with mild to moderate impairment of lung function [ 7 ]. Data on PH prevalence among patients with HP are more limited; most authors report a frequency of 28.3–44.0% [ 8 , 9 , 10 ]. Several studies have confirmed a significant impact of PH on the risk of mortality in patients with IPF [ 7 , 11 , 12 , 13 ].…”