To identify if the delivery of oxygen over consumption of oxygen (DO₂/VO₂) ratio is significantly associated with clinical outcomes such as mortality, need for heart transplantation, or need for a mechanical circulatory support device.

Retrospective cohort study.

Medical and surgical cardiac intensive care units of the Mayo Clinic.

Adult patients (≥18 years old) admitted to the cardiothoracic surgical or cardiac intensive care units between January 2012 and December 2025 were included if they underwent invasive hemodynamic assessment with simultaneous arterial blood gas, mixed venous blood gas, hemoglobin, and mean arterial pressure. Patients were excluded if they had their venous oxygen saturations drawn from a central line or a peripherally inserted central catheter, as well as those admitted for sepsis/septic shock.

No interventions were performed on patients.

DO₂/VO₂ demonstrated a nonlinear association with mortality. Using the median value of 4.73 as a reference point, patients with a DO₂/VO₂ value of ∼2 had the highest likelihood of mortality. Kaplan-Meier analysis using a prespecified cut-point of 5 did not demonstrate any significant relationship with mortality, likely because of the underlying nonlinear relationship. There was no significant association between DO₂/VO₂ ratio and the need for mechanical circulatory support or heart transplantation.

DO₂/VO₂ is a marker of systemic oxygen balance that complements conventional hemodynamic indices. A categorical threshold of 5 did not show an association with clinical outcomes, but continuous analyses did suggest that a low DO₂/VO₂ may identify a high-risk phenotype.