Myocarditis — MRCPsych Paper B MCQ

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ModerateSchizophrenia & PsychosisMyocarditisMRCPsych Paper B

A 31-year-old man with treatment-resistant schizophrenia develops malaise, a temperature of 38.4°C and persistent resting tachycardia on day 18 after starting clozapine. His C-reactive protein is 112 mg/L and high-sensitivity troponin is three times the upper limit of normal. Which is the most likely diagnosis?

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Correct answer: E — Clozapine-induced myocarditis

The correct answer is E, clozapine-induced myocarditis. It usually emerges early in treatment, particularly within the first two months. Persistent resting tachycardia and fever may initially appear non-specific, but the combination of substantially raised CRP and troponin indicates systemic inflammation with myocardial injury. Benign clozapine-associated fever commonly occurs during the first three weeks but should not account for a marked troponin rise. Pneumonia would require supporting respiratory findings and does not best explain myocardial injury. Pulmonary embolism can raise troponin but is less likely given the close temporal relationship to clozapine initiation and inflammatory presentation. Serotonin syndrome requires serotonergic exposure and features such as clonus and hyperreflexia. Suspected myocarditis requires urgent clozapine cessation and cardiology assessment.

Reference: Viatris. Clozapine Viatris 200 mg Tablets, Summary of Product Characteristics, section 4.4: Cardiovascular disorders. Text revised February 2026. https://www.medicines.org.uk/emc/product/102058/smpc