Surveillance of Digoxin Concentrations in Critically Ill Individuals with Heart Failure

Background and Objectives: Digoxin is a pharmacological agent of natural origin that is still occasionally administered in the intensive care unit (ICU). The objective of this study was to assess the efficacy of routine therapeutic drug monitoring (TDM) of digoxin in ICU patients with heart failure. Materials and Methods: This retrospective, single-center study was conducted using data from the ICU database of the Silesian Center for Heart Diseases in Zabrze, Poland. A total of 980 ICU admissions between January 2018 and July 2023 were screened, and 103 patients met the inclusion criteria. Patients were excluded if they had not received digoxin during hospitalization, had only one digoxin level measurement, or did not meet the established criteria for heart failure. Results: Women required significantly lower doses of digoxin compared to men (0.171 ± 0.053 mg vs. 0.224 ± 0.080 mg; p < 0.001). Patients who died had significantly higher serum digoxin concentrations than survivors (1.33 ± 0.59 ng/mL vs. 1.03 ± 0.43 ng/mL; p = 0.003). Similarly, patients with liver failure had higher digoxin levels compared to those without liver dysfunction (1.31 ± 0.58 ng/mL vs. 1.06 ± 0.46 ng/mL; p = 0.016). A weak negative correlation was found between age and the administered dose (r = −0.20; p = 0.048), and a weak positive correlation was observed between serum digoxin concentration and NT-proBNP levels (r = 0.23; p = 0.048). Conclusions: Among ICU patients with multi-organ failure, those with concomitant liver dysfunction tended to reach higher serum digoxin concentrations. Routine therapeutic drug monitoring of digoxin in ICU patients appears beneficial and may help to optimize dosing and reduce adverse effects.