Cumulative Vulnerability in Cardiac Critical Care: A Framework for Understanding Healthcare-Associated Infections and Their Progression to Severe Infection and Sepsis

Background and Objectives: Healthcare-associated infections (HAIs) remain a relevant complication in coronary care units (CCUs), particularly among patients with cardiac dysfunction requiring invasive monitoring and prolonged hospitalization. In this setting, infection occurrence may reflect the cumulative interaction between baseline biological vulnerability and care-related exposure. This study aimed to explore whether a simple cumulative framework integrating these components can describe patterns of HAI occurrence and support early identification of patients at risk for severe infectious complications and sepsis. Materials and Methods: The retrospective cohort study included 870 consecutive adult patients admitted to a tertiary-care CCU. A four-component cumulative framework was constructed using reduced left ventricular ejection fraction (LVEF < 40%), diabetes mellitus, urinary catheterization, and CCU length of stay > 5 days. Each component contributed one point (range 0–4). HAIs were defined according to CDC/NHSN criteria and required microbiological confirmation. Associations between cumulative burden and infection occurrence were assessed using trend analysis and exploratory modeling. Results: HAI occurrence increased progressively across cumulative framework levels, demonstrating a stepwise pattern from low to higher vulnerability strata (p for trend < 0.001). A substantial proportion of infections clustered in patients with higher cumulative values, despite representing a minority of the cohort. Increasing cumulative burden was accompanied by higher observed infection occurrence, supporting a graded association between cumulative vulnerability and infection occurrence. Conclusions: In CCU patients, HAI occurrence appears to reflect the accumulation of biological vulnerability and care-related exposure during hospitalization. A simple cumulative framework may support early identification of patients requiring closer preventive attention and contribute to improved awareness of severe infectious complications in cardiac critical care. Prospective validation is warranted.