What is the effect of Risperidone (risperidone) on ventricular fibrillation (V fib)?

From the Guidelines

Risperidone is not indicated for the treatment of ventricular fibrillation (v fib) and could potentially worsen cardiac conditions due to its QT-prolonging effects, although the QT prolongation is minimal, with a mean QT prolongation of 0–5 ms. V fib is a life-threatening cardiac emergency that requires immediate defibrillation followed by advanced cardiac life support protocols, including epinephrine and antiarrhythmic medications like amiodarone or lidocaine. Risperidone is an atypical antipsychotic medication used primarily to treat schizophrenia, bipolar disorder, and irritability associated with autism, as noted in the evaluation of children with acute mental health or behavioral problems 1.

In a patient with v fib who also happens to be on risperidone for psychiatric indications, the medication should be temporarily held during the acute cardiac event. Once the patient is stabilized, a cardiologist and psychiatrist should evaluate whether risperidone can be safely restarted or if an alternative antipsychotic with less cardiac impact might be more appropriate. Key considerations include:

• The degree of QT prolongation associated with risperidone, which is relatively low compared to other antipsychotics like thioridazine or ziprasidone 1
• The potential for other cardiac risks, such as torsades de pointes, although the evidence suggests that the risk is not significantly increased with risperidone 1
• The importance of managing the patient's psychiatric condition while minimizing cardiac risks

The cardiac risk profile of the patient should be carefully assessed before resuming risperidone therapy, taking into account the potential benefits and risks of the medication in the context of their overall health. It is essential to prioritize the patient's safety and well-being, considering the potential consequences of QT prolongation and other cardiac effects associated with antipsychotic medications 1.

From the FDA Drug Label

The following adverse reactions have been identified during postapproval use of risperidone... These adverse reactions include: ... atrial fibrillation, cardiopulmonary arrest, ... QT prolongation, ... Changes in ECG Parameters Between-group comparisons for pooled placebo-controlled trials in adults revealed no statistically significant differences between risperidone and placebo in mean changes from baseline in ECG parameters, including QT, QTc, and PR intervals, and heart rate

Risperidone and Ventricular Fibrillation (V Fib):

• There is no direct information in the drug label about the use of risperidone in patients with ventricular fibrillation.
• The label does mention atrial fibrillation as an adverse reaction identified during postapproval use, but it does not provide information on the use of risperidone in patients with ventricular fibrillation.
• Additionally, the label mentions that risperidone may cause QT prolongation, which can increase the risk of ventricular arrhythmias, including ventricular fibrillation.
• However, there is no direct information in the label about the safety of using risperidone in patients with ventricular fibrillation 2.

From the Research

Risperidone and Ventricular Fibrillation

• Risperidone is an atypical antipsychotic agent that has been associated with a risk of ventricular arrhythmias, including ventricular fibrillation (VF) 3.
• The risk of VF with risperidone is considered to be lower compared to some other antipsychotic agents, such as thioridazine, pimozide, and sertindole 4.
• However, risperidone can still prolong the QT interval, which is a known risk factor for VF and torsades de pointes 4, 3.
• The risk of VF with risperidone is increased in patients with underlying cardiac pathology, hypokalaemia, hypomagnesaemia, and bradycardia 4.
• Combination of risperidone with other drugs that prolong the QT interval or inhibit its hepatic metabolism can also increase the risk of VF 4.

Management of Ventricular Fibrillation

• Early defibrillation is essential in the management of VF, with a decrease in survival rates of approximately 7%-10% per minute without defibrillation 5.
• Drug therapy, such as beta blockers, can be used to prevent sudden cardiac death in patients predisposed to VF, but its role in the emergency setting is limited 5.
• Other medical therapies, including amiodarone, have not been proven to be consistently effective in preventing VF 5.
• Prevention of arrhythmias through echocardiography, electrocardiography, and laboratory testing is important, even in the emergency setting 5.