Prospective real-time evaluation of the QTc interval variation after low-dose droperidol among emergency department patients

Objective: To assess the QTc interval variation after low-dose droperidol in a population of undifferentiated, stable, and non-agitated patients receiving droperidol in the emergency department. Methods: Prospective cohort study of patients aged ≥12 years of age who received low-dose droperidol (≤ 2.5 mg) for indications other than acute behavioral disturbances. QTc intervals were monitored in real-time during pre-specified observation periods in the ED. Primary outcome was variation of QTc interval after droperidol administration, defined as the maximum delta (change) of QTc interval. Other outcomes included proportion of patients with a QTc ≥ 500 ms after droperidol, delta ≥ +60 ms, and incidence of clinical adverse events. Patients were monitored up to 30 min after IV bolus and up to 46 min after infusion. Results: A total of 68 patients were included (mean age 42.1 years, 66.2% females). The median dose of droperidol was 1.875 mg (range 0.625 mg, 2.5 mg) and 94.1% received droperidol for headache management. Most patients received droperidol as a 2-min bolus (n = 41, 60.3%). The mean maximum delta of QTc interval after droperidol across all 68 patients was +29.9 ms (SD 15). A total of 12 patients (17.6%) experienced a QTc interval ≥ 500 ms during the observation period after droperidol, and 3 patients (4.4%) had a delta QTc ≥ +60 ms. There were no serious arrhythmias, such as TdP, or deaths among the 68 participants in this study (0/68). However, 13.2% (n = 9) had at least one non-serious adverse event including restlessness and/or anxiety. Conclusion: The QTc interval slightly increased after droperidol administration, but these prolongations were brief, mostly below 500 msec and did not lead to serious arrhythmias. The yield of continuous cardiac monitoring in patients receiving low doses of droperidol is likely low.