A 26-year-old man started on clozapine three weeks ago presents with fever of 38.8 degrees Celsius, tachycardia of 128 per minute, and dyspnoea. Examination reveals bibasal crackles. Eosinophil count is elevated and troponin I is mildly raised. Echocardiography shows reduced ejection fraction. What is the most appropriate next step?
- A Continue clozapine and treat with paracetamol
- B Start broad-spectrum antibiotics and continue clozapine
- C Immediately stop clozapine and evaluate for myocarditis ✓
- D Reduce clozapine dose by half and recheck in one week
Correct answer: C. Immediately stop clozapine and evaluate for myocarditis
Explanation
Clozapine-induced myocarditis characteristically occurs within the first four to eight weeks of initiation and presents with fever, tachycardia, chest discomfort, dyspnoea, peripheral eosinophilia, and raised cardiac biomarkers. Because it can progress to fulminant heart failure and death, the drug must be stopped immediately and cardiology evaluation undertaken. Continuing or merely reducing the dose risks fatal deterioration, and attributing the picture to infection while continuing clozapine is the classic fatal error.
Reference: Katzung's Basic and Clinical Pharmacology, 16th ed.
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Written and medically reviewed by the StethoPrep medical team.