May right heart failure cause pulmonary congestion in pulmonary arterial hypertension?

Abstract Aims Recent studies have shown that lung ultrasound-assessed pulmonary congestion is worse in heart failure when pulmonary vascular resistance (PVR) is increased, suggesting a paradoxical relationship between right heart failure and increased lung water content. Accordingly, we wondered if lung ultrasound would reveal otherwise clinically silent pulmonary congestion in patients with pulmonary arterial hypertension (PAH). Methods and results All patients referred for suspicion of PAH in a tertiary center from January 2020 to December 2022 underwent a complete diagnostic work-up including echocardiography, lung ultrasound and right heart catheterization. Pulmonary congestion was identified by lung ultrasound B-lines using an 8-site scan. The study enrolled 102 patients with idiopathic PAH (mean age 53±13; 71% female). WHO functional classes I, II and III were found respectively in 2, 52 and 46% of them. The N-terminal-pro-brain natriuretic peptide (NT-proBNP) was 377 pg/mL [interquartile range, IQR 218, 906]. B-lines were identified in 77 out of 102 patients (75%), with a median of 3 [IQR: 1-5]. At univariable analysis B-lines were positively correlated to male sex, age, NT-proBNP, systolic PA pressure (sPAP), right atrial pressure (RAP), PVR, left ventricular end-diastolic volume and tricuspid annulus plane systolic excursion (TAPSE), and negatively to cardiac output and stroke volume. At multivariable analysis, RAP (p<0.001; Fig 1), TAPSE/sPAP (p=0.001), and NT-proBNP (p=0.04) were independent predictors of B-lines. Conclusion Lung ultrasound commonly discloses pulmonary congestion in PAH. This finding is related to right ventricle to pulmonary artery uncoupling, and may tentatively be explained by increased central venous pressure impeding lymphatic outflow.Figure 1