Survival in Patients With Evidence of Pulmonary Thromboembolism on Ventilation-Perfusion SPECT 12 Weeks After Double Lung Transplantation: A Retrospective Cohort Study

Abstract

Background: Patients who have undergone double lung transplantation (DLTx) are at increased risk of pulmonary thromboembolism (PTE). Although the presence of clinically overt PTE can adversely affect short-term mortality, the prognostic impact of asymptomatic (silent) PTE detected by routine imaging after DLTx is unclear. This study aimed to determine whether PTE identified by routine ventilation-perfusion single-photon emission computed tomography (V̇-Q̇ SPECT) 12 weeks post-DLTx is associated with subsequent all-cause and graft-related mortality. Methods: Single-center retrospective cohort study evaluating 130 DLTx recipients who underwent routine V̇-Q̇ SPECT imaging 12 weeks posttransplant between 2012 and 2017. V̇-Q̇ SPECT scans were assessed for perfusion and ventilation defects indicative of PTE. The association between PTE and mortality outcomes was analyzed using multivariable Cox regression, Kaplan-Meier survival curves, and cumulative incidence functions. Results: PTE was identified in 24.6% (n = 32) of the patients 12 weeks post-DLTx. After 3 months of follow-up, there was no detectable difference in lung function between patients with and without PTE. Moreover, the presence of PTE was not associated with increased hazard ratios for all-cause mortality (HR = 0.72; 95% CI: 0.37–1.41; p = 0.34) or graft-specific mortality (HR = 0.95; 95% CI: 0.42–2.16; p = 0.91). Conclusions: PTE is a frequent finding on routine V̇-Q̇ SPECT 12 weeks post-DLTx that does not inform risk of all-cause or graft-related mortality. These findings suggest that an incidentally detected PTE in asymptomatic patients may not necessitate changes in clinical management for asymptomatic DLTx patients.