Association of renal circulation at acute phase with decongestion level at discharge in patients admitted for acute decompensated heart failure

In patients admitted with acute decompensated heart failure (ADHF), renal hemodynamics may play an important role in the clinical course during hospitalization based on the close cardio-renal relationship. Superb Microvascular Imaging (SMI), distinguished by its advanced clutter suppression capabilities to reveal microflow details, holds promise for evaluating renal circulation. Consequently, our study aims to explore the association between renal circulation as assessed by SMI and the levels of brain natriuretic peptide (BNP) at discharge as an indicator of decongestion status.

In a prospective design, 45 ADHF patients were sequentially examined via renal ultrasound with SMI at discharge. The vascular index (VI) by SMI was calculated as the percentage of blood flow signal area in the region of interest. Then, the intra-renal perfusion index (IRPI) as an index of cyclic variation in VI, was calculated as the maximum VI minus the minimum VI within one cardiac cycle in the ROI divided by the Max.VI (Figure A).

The values of IRPI were as follows: at 12h, 0.70±0.04; at 48h, 0.58±0.05; at 1W, 0.50±0.04; and at discharge, 0.61±0.04. The IRPI measured at 48h showed a stronger correlation with BNP at discharge (r = 0.57, p<0.001) than those at the other three points (Figure B). Patients with higher log BNP at discharge (> 2.31: determined by the median value) had significantly higher IRPI and age, and lower hemoglobin levels at 48h, however, there were no significant differences in estimated glomerular filtration rate, ejection fraction, or systolic pulmonary artery pressure at 48h. The area under the curve of IRPI at 48h for higher log BNP at discharge > 2.31 at discharge was 0.746 (sensitivity 100%, specificity 48%).

Early assessment of renal circulation by SMI around 48 hours after ADHF admission may predict congestion resolution at discharge. This underscores the potential utility of SMI in guiding more aggressive decongestive treatment strategies earlier in ADHF.