Abstract

Objective: To determine the extent of QTc prolongation following administration of an atypical antipsychotic in critically ill patients diagnosed with delirium and to conduct an assessment of risk factors to identify the presence of specific risk factors associated with QTc prolongation in this patient population.

Methods: Patients were included if they were at least 18 years of age, admitted to an Intensive Care Unit (ICU) at the study institution from July 1, 2013 through January 30, 2014, had a documented diagnosis of delirium within their electronic medical record, and received an atypical antipsychotic for delirium during their hospital admission. Excluded patients were those who received an atypical antipsychotic for an indication other than delirium, received fewer than two doses of the atypical antipsychotic, had an atypical antipsychotic documented as a home medication, or demonstrated a lack of EKG data at baseline or post administration of their atypical antipsychotic dose.

Results: Of the 360 patient charts screened, 118 subjects met inclusion criteria. For the study’s primary outcome, the proportion of change from baseline EKG to the first EKG following atypical antipsychotic administration, 72 (61.0%) patients had a decrease in their QTc interval, 1 (0.85%) patient stayed the same, and 45 (38.1%) patients had an increase in their QTc interval. The median change in QTc interval was a decrease of 12.5 msec. Of the 45 (38%) subjects who had an increase in their QTc interval, the mean change from baseline to the first EKG post atypical antipsychotic administration was an increase of 30 msec. Sixty-six (56%) subjects reached steady state while on their first atypical antipsychotic. With respect to the secondary outcome, 40 of 66 (60.1%) had a decrease in their QTc interval, while 26 (39.4%) subjects had an increase in their QTc interval. The median change in QTc interval was a decrease of 10.5 msec. Receipt of a pro-arrhthymic medication was used concomitantly among 25 (21.2%) of patients at baseline. Antibiotics were the most commonly observed class used concomitantly in 39 (21.7%) of the 180 observed total instances of concomitant QTc prolonging agent use, followed by antidepressants (18.9%). Amiodarone was the single most commonly observed agent utilized (10%).

Conclusion: This retrospective analysis of a mixed ICU population demonstrates that following initiation of an atypical antipsychotic, QTc interval increase occurred less frequently then a QTc interval decrease from baseline. Providers should correct modifiable risk factors and minimize concomitant QTc prolonging medications as much as possible.

Keywords: Agitation, atypical antipsychotic, critically ill, delirium, ICU, QTc.