RESUMO
Background: Myocarditis is an infrequent extrapulmonary manifestation of tuberculosis that confers an unfavourable prognosis. Case summary: A 36-year-old man presented to the hospital with palpitations and dyspnoea. Tests revealed the presence of non-sustained ventricular tachycardia, with mild elevation of troponin and C-reactive protein levels. Coronary angiography showed normal results. A cardiac magnetic resonance (CMR) showed moderate hypertrophy, preserved ejection fraction, and an extensive multi-segmental pattern of fibrosis and oedema. An 18F-fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG-PET-CT) scan revealed multiple hypermetabolic adenopathies and patchy cardiac uptake. A tuberculin skin test and interferon-gamma release assay were both positive. An endomyocardial biopsy (EMB) showed inflammation without granulomas; and microbiological stains were negative. Biopsy of an adenopathy revealed the presence of multiple necrotizing granulomas with Langhans cells. Based on the test results and clinical presentation, the suspected diagnosis was tuberculous myocarditis. Treatment with anti-tuberculosis drugs was started. One month later, the presence of mycobacterium tuberculosis (MT) was detected in the lymph node culture. At 7 months of follow-up, the patient remains asymptomatic, ventricular arrhythmias have ceased, and radiological signs of inflammation have resolved. Discussion: Ventricular arrhythmia is one of the clinical manifestations of tuberculous myocarditis. Cardiac magnetic resonance and 18F-FDG-PET-CT imaging are an essential component of the non-invasive evaluation of inflammatory cardiomyopathy. However, a confirmatory biopsy may be required to identify potentially treatable aetiologies. Although the diagnosis of tuberculous myocarditis requires an isolation of MT by staining or culture in EMB, the diagnostic yield is very low. For this reason, extra-cardiac findings may provide the definitive diagnostic clue.
