In-Hospital Mortality Risk Among Transfers to Cardiac Intensive Care Units

Patients treated in tertiary cardiac intensive care units (CICUs) often arrive via transfer from other hospitals. This "transfer population" is poorly described and has been largely excluded from trials in critical care.

The aim of this study was to characterize patients who are transferred from other hospitals to advanced CICUs.

The Critical Care Cardiology Trials Network is an investigator-initiated network of predominantly North American CICUs. Consecutive CICU admissions during annual 2-month snapshots were submitted to the coordinating center (TIMI Study Group) and stratified by transfer vs nontransfer status. Adjustment was made for age, sex, study site, and Sequential Organ Failure Assessment score.

A total of 21,215 admissions (2017-2023) were included in the analysis. Transfers accounted for 38% of admissions and 42% of patient-CICU-days. The primary reason for admission was more likely to be acute coronary syndrome (36% vs 15% for nontransfers, P < 0.001). Transfers were more likely to have shock (35% vs 32%, P = 0.031) and to receive mechanical ventilation (26% vs 17%, P < 0.001), renal replacement therapy (8% vs 5%, P < 0.001), and invasive monitoring (42% vs 34%, P < 0.001). Transfers with shock more frequently received mechanical circulatory support (15% vs 8%, P < 0.001). In-hospital mortality was higher among transfers, accounting for 44% of all deaths (15% vs 11%, P < 0.001; adjusted OR: 1.15 [1.04-1.27]).

Transfers account for more than 1 of 3 admissions to tertiary CICUs, require more complex care, and have higher mortality compared to nontransfers. These findings have implications for designing regional systems of care, hand-off communication, risk-adjusted reporting, and plans of care for this high-risk cohort.