A case report of reversible left ventricular dysfunction due to azathioprine hypersensitivity syndrome.

Background: Hypersensitivity reaction is a rare side effect during immunosuppressive treatment with azathioprine (AZA). Some cases of cardiac involvement have already been reported but causality is notoriously difficult to prove. Case summary: We present the case of a 68-year-old man with two episodes of reversible left ventricular (LV) dysfunction. One month after treatment initiation with AZA, he developed non-specific symptoms, including mild chest pain. In the context of elevated cardiac biomarkers and markers of inflammation, echocardiography showed depressed systolic LV function. Biventricular dysfunction was shown on cardiac magnetic resonance imaging (CMR), but neither myocardial oedema nor late gadolinium enhancement was documented. There was full recovery of LV function after AZA discontinuation. Very similar clinical course and echocardiography findings were observed early after restarting AZA treatment. After definitive cessation of AZA, systolic LV function recovered again and remained stable throughout long-term follow-up. Discussion: Hypersensitivity reaction with cardiac involvement due to AZA is rare. The exact mechanisms underlying AZA-related cardiac dysfunction are still not completely understood, and causality is often difficult to prove. However, because of re-exposure to the drug, which, considered retrospectively, was inappropriate, the effect was clearly apparent in our patient. Knowledge of this potentially life-threatening side effect of AZA treatment is important. AZA must be discontinued promptly if there is any evidence of hypersensitivity reaction.