Cytomegalovirus “Blips” and Rates of Progression to Clinically Significant CMV in Cardiothoracic Transplant Recipients

Background: Guidelines suggest using a highly sensitive, quantitative nucleic acid test (QNAT) for CMV detection; however, there is no standardized threshold to guide preemptive therapy or initiation of CMV treatment. This study sought to characterize the incidence, time course, and management of CMV blips as well as the rate of progression to clinically significant CMV infection (CS-CMVi) following a blip in cardiothoracic transplant recipients. Methods: This is a single-center, retrospective study of heart and lung transplant recipients from January 2018 to August 2024. A CMV blip was defined as the first positive, detectable, and unquantifiable CMV-QNAT. CS-CMVi was defined as either viral load > 1000 IU/mL or initiation of treatment following a blip. Outcomes were assessed within 1 year of transplant. Results: Of the 196 patients included in the study, 58 patients (29.6%) had a CMV blip. A majority of patients (62.1%) were receiving CMV prophylaxis at the time of blip. The median time from transplant to CMV blip was 77.5 days and median time to CS-CMVi, from blip, was 30 days. In the CMV high-risk group (D+/R−), 71.4% (10/14) developed CS-CMVi, compared with 21.4% (9/42) in the moderate risk group (R+) (p = 0.001). Conclusion: In the first year following cardiothoracic transplantation, CMV blips are common occurrences. Patients at high-risk for CMV were more likely to progress to CS-CMVi than moderate risk patients. In the high-risk population, this increased rate of progression gives further evidence that a CMV blip is a risk for the progression of CS-CMVi in the absence of treatment.