History: 36 year-old woman from South America with longstanding history of heart failure was referred for cardiac MR. She was originally diagnosed with “enlarged” heart at the age of 16 by chest X-Ray. Shortly prior to the exam, she presented to a heart-failure center for pre-transplant evaluation due to symptoms of heart failure and severely decreased ejection fraction on echocardiogram, which also revealed biventricular enlargement.
Technique: For the evaluation of cardiac function, short- and long- axis (radial) ECG-gated FIESTA images were acquired. After administration of contrast, myocardial delayed enhancement (MDE) images were acquired to evaluate infiltration/scaring of myocardium.
Ventricular Function: FIESTA images show severely reduced LV function with almost global akinesis. Also, importantly, the RV systolic function is severely impaired as well. The LV EF was calculated to be 16%, and RV EF was 20%. Moderate size pericardial effusion is readily seen on FIESTA images (green arrows).
Myocardial Viability: MDE images show patchy fibrosis of both ventricles. Some hyperenhanced areas spare subendocardium, making myocarditis and not infarction a likely etiology of the fibrosis. Furthermore, the scattered areas of myocardial fibrosis do not adhere to a specific coronary artery distribution pattern.
Another finding, best visualized on MDE images, is clot in LV and RV.
Similarly to the myocardium, thrombi appear very dark on the MDE images.
The MR findings and the history of the patient are compatible with the diagnosis of Chaga’s disease, also known as American trypanosomiasis. It is caused by a parasite, Trypanosoma cruzi, endemic in Central and South America.
The prevelance of the disease varies geographically. Although Chaga’s disease is the leading cause of congestive heart failure in endemic regions, with as much as 50% of population testing positive for T.Cruzi, only a minority of infected individuals (estimated 10-30%) develop symptoms of heart failure. Acute Chaga’s affects mostly children and can cause myocarditis and encephalitis. Manifestations of chronic Chaga’s disease include heart failure, arrhythmias and heart block, and gastrointestinal syndromes caused by megaesophagus or the enlargement of other hollow viscera.