Abstract Body: Background: Prolongation of the corrected QT interval (QTc) is a recognized marker of ventricular repolarization abnormalities and is associated with increased risk of arrhythmias and mortality. However, the prognostic implications of QTc prolongation, particularly in conjunction with Torsade’s de Pointes risk drug (TRD) exposure, remain insufficiently defined in hospitalized patients.
Methods: We conducted a retrospective cohort study using data from the MIMIC-IV database. Restricted cubic spline analysis was employed to identify the QTc threshold associated with elevated in-hospital mortality. Patients were stratified based on QTc duration and TRD exposure. Propensity score matching (PSM) was applied to balance baseline covariates. Cox proportional hazards regression and Kaplan–Meier survival analysis were used to evaluate associations between QTc, TRD exposure, and in-hospital mortality.
Results: A total of 32,461 adult inpatients were included (mean age 64.7 ± 15.4 years; 51.1% male). Restricted cubic spline analysis identified 445 ms as the QTc threshold above which mortality risk increased. Multivariable Cox regression demonstrated that QTc ≥445 ms was independently associated with higher in-hospital mortality (adjusted hazard ratio [HR]: 1.590; 95% confidence interval [CI]: 1.356–1.864; P < 0.001). Kaplan–Meier analysis confirmed significantly reduced survival in patients with QTc ≥445 ms (HR: 1.929; 95% CI: 1.652–2.253; log-rank P < 0.001). These associations remained significant after PSM. Compared with patients without QTc prolongation or TRD exposure, those with either risk factor had higher mortality, while those with both had the greatest risk (HR: 2.965; 95% CI: 2.176–4.039; all P < 0.001).
Conclusions: QTc prolongation ≥445 ms independently predicts short-term in-hospital mortality. TRD exposure further amplifies this risk, highlighting the need to adjust QTc thresholds and enhance monitoring to prevent arrhythmias and improve outcomes.