# Low Absolute Lymphocyte Count Associated With Anti‐Thymocyte Globulin Induction May Be a Predictor of Early Cytomegalovirus Infection in Pediatric Heart Transplantation

## TL;DR

Low lymphocyte counts after anti-thymocyte globulin treatment in heart transplant patients may predict early cytomegalovirus infection.

## Contribution

Identifies low absolute lymphocyte count during induction as a novel predictor of CMV infection in pediatric heart transplant recipients.

## Key findings

- Patients with ALC ≤ 0.3 × 10⁹ cells/L had a 28% CMV viremia rate versus 0% in higher ALC groups.
- Low ALC remained a significant predictor of CMV even after adjusting for CMV serostatus.
- Low ALC groups had higher rejection rates but this difference was not statistically significant.

## Abstract

Cytomegalovirus (CMV) can cause serious morbidity in transplant patients. Lymphocyte depletion by anti‐thymocyte globulin (ATG) may persist for 6 months post‐induction, and lower absolute lymphocyte counts (ALC) may increase the risk for CMV. We sought to find the relationship between ALC at induction and CMV viremia in the first 6 months post‐transplant.

An analysis of transplant recipients within a set period of time with uniformed induction therapy and CMV prophylaxis. ATG was a primary component of induction and ganciclovir or valganciclovir as prevention of CMV infection. The cohort was dichotomized into low ALC (≤ 0.3 × 109 cells/L) and high ALC (> 0.3 × 109 cells/L) based on lowest ALC during the first 14 days and their clinical characteristics analyzed. CMV viremia was defined as PCR value of > 137 IU/mL regardless of symptoms.

A total of 44 patients were included in this study. CMV viremia occurred in 18% (n = 8). Patients were more likely to develop CMV if post‐induction ALC was ≤ 0.3 × 109 cells/L (28% vs. 0%, p = 0.029) and remained significant when adjusted for CMV serostatus (p = 0.04). The total ATG dose (7.5 vs. 4.5 mg/kg) was not predictive of CMV (37% vs. 17%, p = 0.3) nor was treatment for rejection (25% vs. 14%, p = 0.5. Rejection occurred in 7% compared to 20% of patients in the low vs. high ALC group (p = 0.4).

In pediatric heart transplant recipients, there is a higher incidence of CMV if ALC ≤ 0.3 × 109 cells/L during induction, regardless of serostatus. Low ALC levels during induction may identify a high‐risk group that could benefit from an altered CMV prophylactic regimen.

In pediatric heart transplant recipients, there is a higher incidence of cytomegalovirus if ALC ≤ 0.3 × 109 cells/L during induction, regardless of serostatus. Low ALC levels during induction may identify a high‐risk group that could benefit from an altered CMV prophylactic regimen.