Evaluating the Specificity of Capillary Leak Indices in Heart Failure: Implications for Clinical Practice

Highlight

This investigation critically appraises the mechanistic specificity of commonly used clinical indices for assessing capillary leak in a heart failure cohort serving as a negative control. Key highlights include:

• Clinical capillary leak indices—Capillary Leak Index, Vascular Leak Index, and Hematocrit-Albumin Difference—demonstrate weak or absent correlation with the transcapillary escape rate of albumin, an established gold standard for permeability measurement.
• The data indicate these indices may not accurately reflect endothelial permeability changes in chronic and acute-on-chronic heart failure outside of acute inflammatory contexts.
• Findings suggest these indices should be interpreted as context-dependent markers, not universal indicators of capillary leak or endothelial dysfunction.