Atypical antipsychotics are used in cardiac intensive care units (CICU) to treat delirium despite limited data on safety in patients with acute cardiovascular conditions. Patients treated with these agents may be at higher risk for adverse events such as QTc prolongation and arrhythmias. We performed a retrospective cohort study of 144 adult patients who were not receiving antipsychotics before admission and received olanzapine (n = 50) or quetiapine (n = 94) in the Michigan Medicine CICU. Data on baseline characteristics, antipsychotic dose and duration, length of stay, and adverse events were collected. Adverse events included ventricular tachycardia (sustained ventricular tachycardia attributed to the medication), hypotension (systolic blood pressure <90 mm Hg attributed to the medication), and QTc prolongation (QTc increase by ≥60 ms or to an interval ≥500 ms). Twenty-six patients (18%) experienced an adverse event. Of those adverse events, 20 patients (14%) experienced QTc prolongation, 3 patients (2%) had ventricular tachycardia, and 3 patients (2%) had hypotension. Patients who received quetiapine had a higher rate of adverse events (25% vs 6%, p = 0.01) including QTc prolongation (18% vs 6%, p = 0.046). Intensive care unit length of stay was shorter in patients who received olanzapine (6.5 vs 9.5 days, p = 0.047). Eighteen patients (13%) had their antipsychotic continued at discharge from the hospital. In conclusion, QTc prolongation was more common in patients treated with quetiapine versus olanzapine although the number of events was relatively low with both agents in a CICU cohort.
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