Lung Ultrasound, Echocardiography, and Fluid Challenge for the Differential Diagnosis of Pulmonary Hypertension

Abstract

The differential diagnosis between pulmonary arterial hypertension (PAH) and post-capillary pulmonary hypertension (PH) on heart failure with preserved ejection fraction (HFpEF) is sometimes difficult in spite of guidelines-derived standardized step-by-step diagnostic algorithms. We therefore explored the added value of lung ultrasound to previously validated echocardiographic score to right heart catheterization measurements. 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-point 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. The study enrolled 70 patients with PAH and 77 patients with HFpEF. The PAH patients had a higher echocardiographic score (3.5±1.8 vs 1.6±1.5, p <0.001). The HFpEF patients had more B-lines both before (8.1±4.2 vs 5.1±3.0; p <0.001) and after fluid challenge (14.6±5.4 vs 7.6±3.5; p <0.001), and a more important increase (Δ) of B-lines after fluid challenge (6.5±2.9 vs 2.5±1.6; p <0.001). The sensitivity and specificity of the echocardiographic score (cut off ≥2) alone for PAH were 0.91 and 0.49 respectively [area under the curve (AUC) 0.78]. The best diagnostic improvement was observed with addition of ΔB lines + E/e' post fluid challenge to the echocardiographic score, with a significant increase of the AUC (0.98), and (with a cut-off given by the presence of: Echo score ≥ 2 and ΔB lines <4 or E/e' post < 11) a sensitivity of 0.90 (95% CI 0.83;0.97) and specificity 0.84 (95% CI 0.76;0.93)] CONCLUSION: Lung ultrasound combined with echocardiography at baseline and after fluid challenge has an incremental value for the differential diagnosis between PAH and PH-HFpEF.