1346214 - Myocardial tuberculosis presenting as right ventricular cardiomyopathy: evaluation on cardiac MRI

18- years male presented with complaints of shortness of breath and generalized swelling of body for the past 1 month. On examination: jugular venous pressure was raised with pitting oedema of the extremities. Liver was palpable, however no ascites was evident. Auscultation revealed normal heart sounds without any murmur. Laboratory investigations revealed haemoglobin- 17g/dL; total leucocyte count- 6900/mm³; platelet count - 172 x 10⁹/L. Electrocardiograph showed ST segment depression and T-wave inversion. 2D-transthoracic echocardiography (ECHO) demonstrated global hypokinesia, dilated right atrium (RA) and right ventricle (RV), mild mitral regurgitation and severe tricuspid regurgitation. Moderate right and left ventricular systolic dysfunction was also noted (Left ventricular ejection fraction: 25-30%). A working diagnosis of right-sided heart failure was considered and further evaluation was done by cardiac MRI and FDG-PET-CT. Endo-myocardial biopsy revealed moderately dense lymphomononuclear inflammation with formation of granulomas. Special stains for fungi and Mycobacterium were negative. Patient was started on anti-tubercular treatment (ATT) as brain lesion was quite suggestive of tuberculoma and endo-myocardial biopsy demonstrated granulomas. 9-months post anti tubercular treatment follow-up CMR and FDG-PET showed complete resolution of myocardial thickening and brain lesion, confirming the diagnosis of tuberculosis.

Diagnostic Techniques and Their Most Important Findings:

Cardiac MRI showed enhancing lobulated myocardial thickening (10-16mm) involving the RV. Thickening was isointense on T1 and hyperintense on STIR sequences, RV systolic function was compromised (Ejection fraction-25%) and there was transmural enhancement co-localizing to thickened RV myocardium on LGE and T1 TSE (Figure 1). There was significant TR with dilated RA.  IVC and hepatic veins were distended.

FDG-PET scan (Figure 2a) showed intensely increased FDG uptake in the thickened RV wall (SUV max 17.9). In addition a FDG avid lesion was seen in the left medial temporal lobe (SUV max 7.7) which showed thick rim enhancement on post gadolinium MRI (Figure 2b). MR Spectroscopy revealed elevated lipid-lactate peak.

Endo-myocardial biopsy revealed moderately dense lymphomononuclear inflammation with formation of granulomas. Special stains for fungi and Mycobacterium were negative.

9-months post anti tubercular treatment follow-up CMR and FDG-PET showed complete resolution of myocardial thickening and brain lesion (Figure 3a- d)

Learning Points from this Case:

Myocardial tuberculosis without pericardial involvement is rare. Diffuse infiltration of RV presenting as right sided heart failure is extremely rare and should be considered in differential diagnosis where tuberculosis is endemic. On CMR the myocardial thickening may not show characteristic granulomatous or military patterns of involvement as described previously where extra-cardiac involvement may give clue to the diagnosis.