THE DIAGNOSIS
Given her benign cardiac work-up and symptom onset coinciding with the abrupt resumption of high doses of aripiprazole after an 8-month abstinence, the patient’s presentation was attributed to a rather uncommon adverse drug reaction to aripiprazole. This has only been described in a few case reports.
DISCUSSION
Aripiprazole (Abilify) is an atypical antipsychotic frequently used in the treatment of psychiatric conditions, including bipolar disorder and schizophrenia. While the specific therapeutic mechanism is unknown, it is believed that drug efficacy is related to partial agonism at dopamine D2, serotonin 5-HT1A, and serotonin 5-HT2A.1 As aripiprazole works on a variety of receptors involved in other physiologic processes, clinical adverse effects have been reported, most of which are associated with the adrenergic alpha1 receptors.1 These include cognitive impairment and seizures. Cardiovascular adverse effects of aripiprazole include orthostatic hypotension, cardiac arrhythmia, prolonged QT interval, and syncope.1-5
Selective serotonin reuptake inhibitors (SSRIs) such as sertraline (Zoloft) have also been shown to cause cardiac arrhythmia and syncope.6 Although sertraline may have contributed to the patient’s cardiac symptoms, it is more likely that the aripiprazole was the direct cause, as she remained asymptomatic while on a therapeutic dose of sertraline. Furthermore, aripiprazole is primarily metabolized though hepatic CYP2D6, which sertraline has been shown to inhibit.1,7 Therefore, the concomitant use of sertraline with no initial taper of either medication likely led to an increased effective dose of aripiprazole in our patient and subsequently to her presentation.
Few prior cases have identified aripiprazole as a cause of antipsychotic-associated bradycardic response.8 Based on the Adverse Drug Reaction Probability Scale, often referred to as the Naranjo Scale, we believe this to be a probable adverse response in our patient.9 Bradycardia followed a reasonable temporal sequence after aripiprazole use with a response previously described in the literature. Symptoms also improved after discontinuation of the drug and other etiologies of the bradycardia were ruled out.
Our patient was discharged with a 30-day cardiac event monitor and a scheduled appointment with Cardiology.
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