Clinical and Radiographic Characteristics Associated With Pulmonary Artery Enlargement in Pulmonary Tuberculosis

Abstract RATIONALE: Pulmonary hypertension (PH) is a well-recognized driver of morbidity and mortality in numerous chronic lung diseases. Despite this increasing awareness, the prevalence and risk factors associated with PH in pulmonary tuberculosis (PTB) remain poorly characterized. This study aims to test the hypothesis that the radiographic severity of lung injury and burden of fibrocavitary disease at the time of PTB diagnosis will be associated with pulmonary artery (PA) enlargement on high-resolution computed tomography (HRCT), an independent predictor of PH. METHODS: In this cross-sectional nested study within an ongoing prospective observational cohort in Johannesburg, South Africa, adults with and without HIV were enrolled within two weeks of initiating standard four-drug therapy for newly diagnosed, first-time episodes of drug-susceptible PTB. All participants had moderate-to-severe pulmonary disease based on chest x-ray and completed HRCT imaging upon enrollment. Semi-quantitative scoring of HRCT imaging was independently performed by a clinical radiologist. Comparisons were made using Student's t-test and Wilcoxon rank-sum test as indicated to identify unadjusted clinical and radiographic associations of PA enlargement, defined as a PA diameter >3.0cm at the level of the PA bifurcation. RESULTS: Among 151 TB and HIV/TB co-infected participants, the prevalence of PA enlargement seen on HRCT at the time of PTB diagnosis was 25% (n=38). Participants with PA enlargement were more often male, significantly older (45.2 ± 13.5 vs. 35.9 ± 9.4 years old; p = <0.001) and had more extensive cigarette smoking history (10.1 ± 9.8 vs. 5.2 ± 5.6 pack-years; p = 0.03) than those without PA enlargement. Participants with PA enlargement also had a greater extent of overall lung damage (p=0.04) with more advanced emphysema (p<0.01) and fibrosis on HRCT (p=0.05). There was no significant difference in the extent of consolidation and cavitary lung disease on imaging, or presence of HIV coinfection, diabetes, heart disease, and prior lung disease between the two groups. Results remained consistent without a significant change in the measures of association when analyses were restricted to only male participants (data not shown). CONCLUSIONS: This study reveals a high prevalence of PA enlargement (25%) among a cohort with newly diagnosed moderate-to-severe radiographic PTB. The severity of radiographic emphysema and fibrosis were significantly associated with PA enlargement, suggesting chronic lung injury may contribute to the development of PH in PTB. Further research to investigate the burden and drivers of TB-associated PH is needed to meaningfully improve outcomes for millions of TB survivors each year.