Antipsychotic-Associated Hypothermia With Bradycardia and QT Prolongation in an Older Adult

Second-generation antipsychotics may cause rare but potentially life-threatening disturbances in thermoregulation and cardiac conduction. We report a 92-year-old man with severe frailty, cognitive impairment, pre-existing sinus bradycardia, and right bundle branch block who presented on three occasions with recurrent hypothermia, progressive bradycardia, and altered mental status. The initial episode was attributed to an Enterobacter cloacae complex urinary tract infection. However, symptoms recurred despite negative repeat urine cultures, culminating in profound hypothermia, hypotension, a heart rate of 26 beats/min, and marked QT interval prolongation. No persistent infectious, endocrine, environmental, or acute neurologic cause was identified. Medication reconciliation subsequently confirmed a recent increase in quetiapine from 25 mg to 100 mg nightly, with concurrent risperidone administration. A suspected adverse reaction to second-generation antipsychotics was suspected, with advanced age, frailty, dehydration, and recent infection considered predisposing factors. Quetiapine and risperidone were discontinued, after which body temperature and the QT interval normalized within five days, heart rate returned to baseline, and mental status, renal function, leukocyte count, and platelet count recovered. This case highlights the importance of medication reconciliation and early recognition of antipsychotic-associated hypothermia in frail older adults.