UCSF

Purpose: QT and QTc (heart rate corrected) prolongation on the electrocardiogram (ECG) is associated with an increased risk for torsade de pointes (TdP). In at-risk hospitalized patients, it is common practice to obtain a standard 12-lead ECG to assess QT/QTc prolongation, which is costly and time-consuming. Our hospital recently introduced bedside monitors in the intensive care unit (ICU) that include software that continuously measures the QT/QTc. However, only six ECG leads are available on the bedside monitor, rather than all 12-leads offered on a standard ECG. Therefore, the purpose of this study was to evaluate the agreement between computerized QT/QTc measurements from the bedside monitor (six leads) and a standard 12-lead ECG. Design: Prospective observational study in three adult intensive care units (ICUs). Methods: QT/QTc measurements were obtained from a convenience sample. Patients with a standard 12-lead ECG that could be closely matched in time to bedside monitoring data were included. The agreement between the two methods (bedside monitor [six-leads] versus standard 12-lead), was evaluated using Bland-Altman analysis. Results: A total of 60 patients were included. The mean bias difference for QT measurements between the bedside monitor (six-leads) versus the standard 12-lead was not statistically different (β=-2.47, 95% CI=5.50 to -11.05; p=0.44; limits of agreement (LOA)=-64.37 to 59.44). Similar non-statistical differences were observed for QTc (β=-3.20, 95% CI=5.50 to -11.05; p = 0.44; LOA=-67.43 to 61.03). Conclusion: There was good agreement for both QT and QTc measurements between six-lead bedside monitor derived values and those obtained with a standard 12-lead ECG. These pilot data are promising and suggest QT/QTc measurements generated from bedside monitors may be an acceptable alternative to obtaining additional standard 12-lead ECGs for assessing QT/QTc prolongation. However, an evaluation of agreement between these two methods in a larger sample is warranted.