Atrial tachycardia associated with risperidone

To the Editor

Atypical antipsychotics are associated with a number of adverse events involving the cardiovascular system. Specifically, the cardiovascular side effect profile of risperidone includes orthostatic hypotension, sinus tachycardia, atrial fibrillation and QT lengthening (Drici and Priori, 2007). We describe the onset of atrial tachycardia related to risperidone prescribed for treatment-resistant schizoaffective disorder. This, to our knowledge, is not a well-recognized potential cardiovascular side effect of risperidone.

Mrs X, an 80-year-old widow, had a diagnosis of severe schizoaffective disorder with good interepisode functioning. Her medical history was noted for hypertension managed on a beta blocker and angiotensin-converting enzyme inhibitor as well as hypercholesterolaemia. She was receiving inpatient treatment for a depressive relapse with psychotic symptoms. While depressive symptoms had improved on venlafaxine XR 225 mg mane and mirtazapine 15 mg nocte, psychotic symptoms persisted despite being on up to 20 mg of olanzapine daily. This was therefore cross titrated to risperidone increasing gradually to 2 mg per day. The initial cross titration went well, and there was improvement in psychosis.

Unfortunately, after approximately a week on risperidone monotherapy, Mrs. X developed an episode of atrial tachycardia requiring transfer to a cardiology specialist unit. Previous electrocardiograms including those as an outpatient, past admissions and the current admission were unremarkable. While in the cardiology unit, she was investigated for the cause of the atrial tachycardia and no underlying cause was identified. The cardiologist recommended atrial ablation. Arrangements were in place for this treatment to proceed. Coincidentally, Mrs. X’s daughter, a medical practitioner, through her own research found an association between risperidone and atrial tachycardia. The patient’s daughter strongly advocated to cease risperidone in an attempt to avoid ablation therapy. Mrs. X’s risperidone was ceased. The atrial tachycardia resolved following the cessation of risperidone and the ablation procedure cancelled. She was transferred back to the inpatient psychiatric unit where Aripiprazole was commenced titrating to a dose of 15 mg. Mrs. X’s mental state improved and was able to achieve symptom remission in a few weeks. There was no recurrence of atrial tachycardia.

The temporal relationship between the commencement of risperidone treatment and onset of atrial tachycardia, as well as the return to normal cardiac rhythm upon cessation of risperidone, is compelling evidence that risperidone was the responsible agent. Our literature review revealed only one other published case of atrial tachycardia induced with risperidone – a case of multifocal atrial tachycardia in an adolescent receiving risperidone for treatment of behavioural disorder in autism (Oner et al., 2016). This case adds to the limited literature around this potential cardiac side effect. In addition, the manner that we became aware of the potential role of risperidone in precipitating atrial tachycardia reinforces the importance of not only listening to families but also remaining curious about our patients and in particular those without advantages such as sophisticated medical knowledge readily available.