Key clinical message: Mycoplasma myocarditis is a rare but potentially serious condition that can cause inflammation of the heart muscle, leading to arrhythmia and heart failure. It is important to consider this condition in the differential diagnosis of young patients presenting with unexplained signs of heart failure and SVT, even in the absence of signs of myocardiocytolysis and extra-cardiac disease.
Abstract: Mycoplasma pneumoniae infections are often underdiagnosed as a great proportion of patients remain asymptomatic, pauci-symptomatic, or exhibit varying presentations. M. Pneumoniae manifestations can affect different systems, including the heart, with the potential to lead to high degree of morbidity and debilitating sequelae. Here we present an atypical case of M. Pneumoniae associated myocarditis which presented with sustained refractory SVT, symptoms of heart failure, and with no signs of myocardiocytolysis, pulmonary involvement, or systemic infection. Given the lack of signs of myocardial inflammation, the patient was initially misdiagnosed with tachycardia induced cardiomyopathy (TIC), but later correctly diagnosed after showing signs of pneumonia during the hospitalization. The patient received the appropriate antibiotic treatment in addition to corticosteroids, was discharged on the 15th day of hospitalization, and completely recovered after 1 month with no arrhythmia recurrence and normalization of ventricular function.
Keywords: heart failure; mycoplasma pneumoniae myocarditis; myocarditis induced arrhythmia; supraventricular tachycardia; sustained refractory.
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