Predictors of B-line count in hospitalized patients with COVID-19

B-lines on lung ultrasound (LUS) are nonspecific signs of increased lung density, which can be secondary to pulmonary congestion, pneumonia, or fibrosis. While its use is recommended in acute heart failure (HF), its value in non-HF populations is less clear.

We prospectively analyzed hospitalized non-ICU patients ≥18 years old with confirmed laboratory diagnoses of COVID-19. We aimed to identify associations between 8-zone LUS findings and clinical, laboratory, and echocardiographic data, and 30-day mortality using trend and regression analyses.

Among 270 patients (mean age 69 ± 14 years, 58% male, and 11% with prior HF) the median time from hospital admission to LUS was 4 days [interquartile range (IQR) 2-8]. In total, 263 (97%) had ≥1 B-line [median B-line number 13 (IQR 9-22)], and the median left ventricular ejection fraction (LVEF) was 59 (IQR 54-63). In adjusted models, having more B-lines was associated with higher levels of C-reactive protein, with an incidence rate ratio (IRR) of 16% (95%CI: 8%-24%) per log-unit increase (P < 0.001) and higher Early Warning Score [IRR 5% (95%CI: 2%-8%) per point, P = 0.003]. Higher tricuspid regurgitation gradient was associated with more B-lines: IRR 2% (95%CI: 1%-3%) per mmHg, P = 0.001). However, left ventricular function measures and NT-proBNP concentrations showed no significant association with B-lines. Furthermore, B-lines were not associated with 30-day mortality.

Among patients with COVID-19, B-lines on LUS are associated with markers of infectious disease severity and pulmonary hypertension, but not with markers of left-sided HF.