A case report on clozapine-induced ventricular ectopics: a fatal adverse drug reaction

Background Clozapine is one of the most efficacious antipsychotic drug used for the treatment-resistant schizophrenia; it is sometimes associated with serious adverse reactions like agranulocytosis, myocarditis, cardiac rhythm disturbances, etc. Case presentation A 30-year-old patient with a primary diagnosis of paranoid schizophrenia (ICD code - F20.05) was on regular prescription for 6 years. Due to refractoriness, the patient was initiated on tablet clozapine. After 45 days of clozapine therapy, he presented with the complaints of worsening of positive symptoms and sudden falls associated with a brief period of unresponsiveness for which the patient was admitted for evaluation. After stabilization of the patient, it was concluded that he was suffering from ventricular ectopics based upon cardiac investigations like electrocardiogram (ECG) and Holter monitoring. Upon causality assessment between the adverse drug reaction (ADR) and the suspected drug using Naranjo Scale and WHO causality assessment scale, the ADR was found to be probable. Conclusions This case report will help to keep physicians vigilant about the rare cardiac side effects of clozapine and to do regular ECG monitoring of the patients who are on clozapine. Moreover, this case report generates the evidence of clozapine-induced arrhythmia, which is needed to be quantified with aggressive study design and there is a need to study the dose-dependent relationship of clozapine-induced arrhythmia.