Absolute Lymphocyte Count: a Predictor of Positive Serum PCR for Trypanosoma cruzi in Patients with Chagas Disease Undergoing Heart Transplantation.

Background: It is unknown whether lymphopenia is a risk factor for the reactivation of Chagas disease in heart transplantation (HTx), as recently described in the reactivation of cytomegalovirus in transplant patients.

Objective: To evaluate whether lymphopenia in the perioperative period of heart transplantation is related to early Trypanosoma cruzi parasitemia.

Methods: This observational, retrospective study analyzed a sample from January 2014 to January 2023). Parasitemia was evaluated in the first 3 months after HTx using serum polymerase chain reaction (PCR) and compared with the total lymphocyte count in the perioperative period of HTx using receiver operating characteristic curves. Baseline characteristics were compared with PCR for Chagas using independent Cox proportional hazards models. A significance level of 5% was adopted.

Results: The sample (n = 35) had a mean age of 52.5 ± 8.1 years, and 22 patients (62.8%) had positive PCR for Chagas. The mean lowest lymphocyte values in the first 14 days after HTx were 398 ± 189 and 755 ± 303 cells/mm3 in patients with and without parasitemia, respectively, within 3 months after HTx (area under the curve = 0.857; 95% confidence interval: 0.996 to 0.718, sensitivity and specificity of 83.3% and 86.4%). A cutoff value of less than 550 lymphocytes/mm3 was determined as a risk factor for the presence of parasitemia. Patients with lymphocytes < 550 units/mm3 in the first 14 days after HTx presented positive PCR in 80% of cases. For every increase of 100 lymphocytes/mm3, the risk of PCR positivity was reduced by 26% (hazard rate ratio = 0.74; 95% confidence interval: 0.59 to 0.93, p = 0.009).

Conclusion: There was an association between lymphopenia in the perioperative period of HTx and early T. cruzi parasitemia detected by PCR.