Methotrexate A Cause of Myocarditis, Myth or Reality?

Methotrexate, widely used as an antimetabolite in cancer therapy and for systemic diseases such as rheumatoid arthritis, has known toxic effects on rapidly proliferating cells, but its role in myocarditis remains controversial. This article presents a case of a 56-year-old diabetic patient treated with methotrexate for rheumatoid arthritis who developed acute myocarditis—characterized by lower limb edema, segmental left ventricular dysfunction, and late enhancement on cardiac MRI. Infectious and toxic etiologies were ruled out, and symptoms rapidly resolved upon discontinuation of methotrexate and initiation of symptomatic therapy, suggesting a probable drug-induced cause. Although a definitive causal link could not be established without myocardial biopsy, the report underscores the importance of careful monitoring for cardiac side effects in patients on immunosuppressive therapy and recommends prompt discontinuation of implicated drugs when acute heart failure emerges.