Accurate hemodynamic assessment remains important in the management of patients supported with left ventricular assist devices (LVADs). An observational study published in the Journal of Cardiac Failure compared direct and indirect Fick methods for cardiac index (CI) estimation in patients with LVADs and evaluated their association with clinical outcomes.

The analysis included adult patients who underwent right heart catheterization at a university hospital between March 2021 and April 2025. Logistic regression models evaluated associations between CI estimation methods and a composite endpoint of death, heart transplantation, or heart failure hospitalization.

Findings

• The study included 140 patients undergoing 151 right heart catheterization procedures with simultaneous oxygen consumption measurements.
• Correlation between direct Fick CI and indirect Fick CI estimates was poor across commonly used formulas.
• Coefficients of determination (R²) between direct and indirect methods were 0.37 for Dehmer, 0.36 for LaFarge, 0.25 for Bergstra, and 0.42 for BMI-adjusted Dehmer methods.
• Differences greater than 25% between indirect and direct Fick estimates were common.
• In multivariable analysis, only direct Fick CI was associated with the composite outcome of death, heart transplantation, or heart failure hospitalization (OR 0.440; p=0.022).

The analysis showed poor correlation between indirect and direct Fick cardiac index calculations in patients with LVADs. A lower directly measured cardiac index was associated with higher odds of death, heart failure hospitalization, or heart transplantation.