Absence of Cardiac Side Effects During Treatment of Schizophrenia With Risperidone in a Patient With Wolff-Parkinson-White Syndrome

Sir: Excessive prolongation of the QT interval can predispose to a peculiar ventricular arrhythmia called torsade de pointes, or sudden cardiac death. QT prolongation has been found to occur with some older conventional and newer atypical antipsychotics.¹ Nevertheless, the recent literature suggests that atypical antipsychotics are not associated with torsade de pointes except in the case of a concomitant risk factor (e.g., polypharmacy, overdose, restraint, substance misuse, electrolyte imbalance).^1,2

The risk for QT prolongation does not seem to be the same for all atypical antipsychotics. Olanzapine seems to present a quasi-inexistent risk¹; risperidone, quetiapine, aripiprazole, and clozapine present weak to moderate risks²; and ziprasidone presents higher risks.¹ Sertindole has been associated with QT prolongation leading to fatal cardiac arrhythmias.

Other cardiovascular risks associated with antipsychotic use include cardiac factors such as long QT syndromes, ischemic heart disease, myocarditis, and sinus bradycardia.³ A case report of olanzapine-induced corrected QT (QTc) prolongation in a patient with Wolff-Parkinson-White (WPW) syndrome has recently been published.⁴

We report the clinical case of a 35-year-old man with DSM-IV schizophrenia and WPW syndrome who received treatment with risperidone.

Case report. In May 2004, Mr. A was hospitalized due to the exacerbation of paranoid delusions and auditory hallucinations. Because of compliance issues, we decided to administer long-acting injectable risperidone, 50 mg, allied with an oral treatment of risperidone, 2 mg/day, during the first month. Concomitant treatment consisted of trazodone, 100 mg/day, and lorazepam, 15 mg/day. Before the start of treatment, the QTc interval was 420 ms. One week later, it was at 452 ms and 2 weeks later, 469 ms. A second injection of risperidone, 50 mg, was then administered. Subsequently, the patient refused further injections. Oral treatment with risperidone, 6 mg/day, was then administered. One month later, his psychotic symptoms improved, and his QTc interval was 472 ms.

Life-threatening ventricular arrhythmias in WPW syndrome are related to a rapid anterograde conduction throughout the bypass tract and are not related to torsade de pointes. Mr. A exhibited paroxysmal palpitations, and the baseline electrocardiogram showed intermittent pre-excitation from a left lateral accessory bypass tract. Pre-excitation regressed during sinus tachycardia with an enhanced conduction in the normal conduction system, suggesting a long refractory period within the bypass tract and a low risk for life-threatening ventricular arrhythmias.

In conclusion, WPW syndrome per se seems not to be a contraindication for atypical antipsychotics, and standard safety measures such as the regular measurement of the QTc interval and the avoidance of concomitant QT-prolonging drugs should be sufficient precautions when treating WPW patients with atypical antipsychotics.