Exercise-induced B-lines identify worse functional and prognostic stage in heart failure patients with depressed left ventricular ejection fraction.

Abstract

Exercise stress echocardiography (ESE) is recommended by the European Society of Cardiology guidelines for the evaluation of heart failure (HF) patients. Recently, lung ultrasound (LUS) has been proposed for the assessment of extravascular lung water through B-lines. The aim of this study was to assess B-lines during ESE in HF. Standard transthoracic and LUS evaluation was performed during semi-supine ESE in 103 NYHA class I-III HF patients (76 male; mean age 64 ± 12 years) with depressed left ventricular ejection fraction (35 ± 8%). B-lines were measured by scanning 28 intercostal spaces on antero-lateral chest, both at rest and at peak stress. Resting plasma B-type natriuretic peptide (BNP) levels and exercise capacity during cardiopulmonary testing with peak oxygen uptake (peak VO2 ) were assessed in all patients. All patients were followed up for a median of 8 months (first quartile, 6; third quartile, 11). LUS was feasible and interpretable in all subjects. The overall number of B-lines increased from rest (median 5, interquartile range 0-10) to peak stress (median 12, interquartile range 0-45) (P < 0.0001). The number of stress B-lines was closely correlated with resting log-BNP (r = 0.88, P < 0.0001) and peak VO2 (r = -0.90, P < 0.0001). During follow-up, 37 events occurred: 10 deaths, 23 re-hospitalizations for acute HF, and 4 non-fatal myocardial infarctions. Twelve-month event-free survival was 95% in the 36 patients with stress B-lines <30 (best cut-off identified by receiver operating characteristic curve analysis) vs. 7% in patients with ≥30 B-lines (P < 0.0001). B-lines are easy to obtain, frequent in HF patients, and often increase during ESE. Adverse events were more frequent in patients with more B-lines during ESE.