Parasitic Persistence in Left Atrium Remnants of Chronic Chagasic Patients Submitted to Bicaval Heart Transplantation

To the Editor, Heart transplantation (HT) is an effective treatment for advanced stages of chronic chagasic cardiomyopathy, a disease caused by infection with the protozoan Trypanosoma cruzi. In addition to the usual complications of HT, the patient may experience reactivation of the infectious disease.1 Reactivation of Chagas disease occurs through proliferation and dissemination of T. cruzi parasites, which may be hidden in various organs and tissues, particularly in the heart.2 Reactivation is closely related to the intensity of immunosuppression to which the patient is submitted.1,3 The superior wall of the left atrium of the recipient with the terminal portion of the pulmonary veins is maintained in bicaval HT. The left atrial anastomosis is done with remnants of the recipients’ left atrium, and not with the pulmonary veins separately, which could lead to pulmonary venous anastomotic stenosis.4 To test the hypothesis of T. cruzi persistence in the superior wall of the left atrium of chronic chagasic patients submitted to bicaval HT, we evaluated histologically the left atrial remnants of the recipient in five patients who died up to 1 year after surgery. The removed left atrial segments had a rectangular shape, measuring 20 × 15 mm. They were serially sectioned and included in two paraffin blocks, which contained a total of six to eight atrial fragments. The paraffin blocks were serially sectioned, and three slides of each block were collected for hematoxylin-eosin (HE) staining and another three for immunohistochemical detection of T. cruzi antigens. The patients’ age at death ranged from 43 to 62 years and four of them were women. Two patients died of acute rejection, two of pulmonary infection andone of primary graft dysfunction.Death occurred from 8 days to 10months after HT. Mild mononuclear myocarditis was present in 4 cases, fibrosis in two cases and multifocal recent myocardial necrosis in two cases. We detected three parasitic nests of T. cruzi in the left atrial segment of one patient, who died 8 days after surgery. Detection was confirmed by positivity through immunohistochemistry for T. cruzi antigens (Figure 1). In this brief study, we confirmed the possibility of parasite persistence in left atrial remnants (superior wall of the left atrium) of chronic chagasic patients submitted to bicaval HT. The presence of T. cruzimicroorganisms (nests) at that location could be the source of the protozoans for the occurrence of reactivation. The reduction of the left atrial remnants of the chagasic patient by changing the HT technique from bicaval to total may have an impact F IGURE 1 A nest of T. cruzi parasites (arrow) in left atrial remnants of a chagasic patient submitted to bicaval heart transplantation. Notemild lymphocytic myocarditis in the right half of the image. Immunohistochemistry for T. cruzi antigens.