Association between lung ultrasound findings and invasive exercise haemodynamics in patients with undifferentiated dyspnoea

Abstract

Aims: Dyspnoea is common in heart failure (HF) but non-specific. Lung ultrasound (LUS) could represent a non-invasive tool to detect subclinical pulmonary congestion in patients with undifferentiated dyspnoea.

Methods and results: We assessed the feasibility of an abbreviated LUS protocol (eight and two zones) in a prospective pilot study of 25 ambulatory patients with undifferentiated dyspnoea undergoing clinically indicated invasive cardiopulmonary exercise testing (iCPET) at rest (LUS 1) and after peak exercise (LUS 2). We also related LUS findings (B-lines) to invasive haemodynamics stratified by supine pulmonary capillary wedge pressure (PCWP) (Congestion, >15 mmHg; Control, ≤15 mmHg). All enrolled patients (median age 68, 60% women, 32% prior HF, median ejection fraction 59%) had interpretable LUS 1 images in eight zones, and 20 (80%) had adequate LUS 2 images. LUS images were adequate in two posterior zones in 24 patients (96%) for LUS 1 and 18 (72%) for LUS 2. Although B-line number was numerically higher in the Congestion group at rest and after peak exercise, this difference did not reach statistical significance. In the entire cohort, there was an association between B-lines and rest systolic pulmonary artery pressure (r = 0.46, P = 0.02) and PCWP (r = 0.54, P = 0.005). There was an inverse relationship between B-lines and peak VO₂ (r = -0.65, P = 0.002).

Conclusions: Among ambulatory patients with undifferentiated dyspnoea, an abbreviated LUS protocol before and after iCPET is feasible in the majority of patients. B-line number at rest was associated with invasively measured markers of haemodynamic congestion and was inversely related with peak VO₂ .

Keywords: Congestion; Dyspnoea; Invasive haemodynamics; Lung ultrasound.