Lung ultrasound, echocardiography, and fluid loading for the differential diagnosis of pulmonary hypertension

Abstract Background There may be interest in combining echocardiography and lung ultrasound for the differential diagnosis between pulmonary arterial hypertension (PAH) and post-capillary pulmonary hypertension on heart failure with preserved ejection fraction (PH-HFpEF). Methods Patients referred for PH underwent a right heart catheterization, echocardiography and lung ultrasound before and after rapid infusion of 7 ml/kg of saline. A 7-points echocardiographic score based on cardiac chamber dimensions and estimates of filling pressures was implemented for the prediction of pre-capillary PH. Pulmonary congestion was identified by lung ultrasound B-lines. Results The study enrolled 70 patients with PAH and 77 patients with HFpEF. The PAH patients had a higher echocardiographic score (3.5±1.8 v 1.6±1.5, p <0.001). Figure 1 represents the typical baseline echocardiographic components of pre-capillary pulmonary hypertension prediction score and pre- and post-fluid loading lung ultrasound imaging from patients with PAH and HFpEF respectively. The HFpEF patients had more B-lines both before (8.1±4.2 vs 5.1±3.0; p <0.001) and after fluid loading (14.6±5.4 vs 7.6±3.5; p <0.001), and a more important increase (Δ) of B-lines after fluid loading (6.5±2.9 vs 2.5±1.6; p <0.001). The sensitivity and specificity of the echocardiographic score alone for PAH were 0.91 and 0.49 respectively [area under the curve (AUC) 0.78]. The AUC for PAH was improved by addition of smaller ΔB-lines to the echocardiography prediction score after fluid loading, with significant increase in sensitivity [0.94 (95% CI 0.89;1.00)] and specificity [0.91 (95% CI 0.84;0.97)] and a positive predictive value of 0.90 (CI 0.84;0.97) and a negative predictive value of 0.95 (CI 0.89;1.00). Figure 2 represents the bar plot of AUC for echocardiographic score, pre- fluid loading B-lines, delta E/e', delta B-lines, post- fluid loading E/e', post- fluid loading B-lines, in ascending order. Conclusion Lung ultrasound combined with echocardiography at baseline and after fluid loading has an incremental value for the differential diagnosis between PAH and PH-HFpEF.Figure 1Figure 2