Kidney Week

Abstract: TH-PO1033

Prognostic Effect of Early vs. Late Post-Transplant Thrombotic Microangiopathy

Session Information

• Transplantation: Clinical - Outcomes, Malignancy, and Pathology
  October 22, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Transplantation

• 2002 Transplantation: Clinical

Authors

• Calvo Jiménez, José Fernando, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Mexico City, CDMX, Mexico

José Fernando Calvo Jiménez, MD

• Zuñiga Gonzalez, Erick Yasar, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Mexico City, CDMX, Mexico

Erick Yasar Zuñiga Gonzalez, MD, MEd

• Camacho Murillo, Luis Agustín, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Mexico City, CDMX, Mexico

Luis Agustín Camacho Murillo, MD

• Morales Buenrostro, Luis Eduardo, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Mexico City, CDMX, Mexico

Luis Eduardo Morales Buenrostro, MD

Background

Post-transplant thrombotic microangiopathy (TMA) involves complement activation, endothelial dysfunction, and immune-mediated vascular injury, frequently associated with antibody-mediated rejection (ABMR). This study evaluated the impact of TMA timing and phenotype on kidney allograft survival.

Methods

We conducted a single-center retrospective study including kidney transplant recipients with biopsy-proven TMA diagnosed between 2010 and 2024. Clinical, laboratory, and histopathologic features at diagnosis were analyzed. Patients were classified as early (<3 months) or late (>3 months) post-transplant TMA. Graft survival was evaluated according to timing of presentation and associated prognostic factors.

Results

Fifty patients were included. Median age at transplantation was 29 years, and 58% received kidneys from living donors. Overall graft survival after TMA diagnosis was 48% at 10 years [Figure1A]. Early TMA occurred in 17 (34%) patients and late TMA in 33 (66%). Among early cases, 11 (64%) responded to therapy, whereas 6 (36%) were non-responsive. Early biopsies predominantly showed acute lesions (77%); only responders lacked microvascular inflammation (MVI) and C4d deposition. Late TMA was classified as active ABMR-associated (n=13) or chronic TMA (n=20). ABMR-associated TMA showed higher MVI scores, more C4d positivity, greater interstitial fibrosis, and higher dialysis requirements at presentation. This phenotype had the highest graft loss rate (92%). Early presentation tended to have better outcomes than late presentation (log-rank p=0.08). Stratified by phenotype, early responsive TMA had the best graft survival (100% at 10 years), whereas early non-responsive and ABMR-associated TMA had markedly poorer outcomes [Figure1C].

Conclusion

Kidney-limited TMA reflects severe endothelial and immune injury with heterogeneous outcomes. Early responsive forms show favorable graft survival, whereas non-responsive and ABMR-associated phenotypes predict graft loss.