Post-transplant cyclophosphamide (PT-Cy) is widely used for graft-versus-host disease prophylaxis following allogeneic hematopoietic stem cell transplantation (alloHSCT). However, concerns persist regarding its potential cardiotoxic effects, particularly in the early post-transplant period. This monocentric retrospective observational study, published in the Canadian Journal of Cardiology, assessed the relationship between PT-Cy use and early cardiotoxicity occurring within 100 days after alloHSCT.

All consecutive patients undergoing alloHSCT at Saint-Louis University Hospital between July 2011 and July 2023 were included. The primary endpoint was a composite of early cardiotoxicity, including cardiovascular death, heart failure (HF), myocarditis, pericardial disease, cardiac arrhythmias, and acute arterial events. Propensity score matching (1:1) was applied to balance baseline characteristics between patients receiving PT-Cy and those who did not. Predictors of cardiotoxicity were evaluated using Fine-and-Gray subdistribution hazard models.

Among 1,381 patients, 143 (10%) developed early cardiotoxicity. HF was the most frequent event (53%), followed by arrhythmias (20%) and pericardial disease (19%). Independent predictors included age, prior HF, prior cancer therapy–related cardiac dysfunction, hypertension, and PT-Cy use (subdistribution hazard ratio [sHR] 1.62; p=0.022). After matching, PT-Cy remained significantly associated with cardiotoxicity (hazard ratio [HR] 2.00; p=0.035).

PT-Cy use was associated with increased early cardiotoxicity risk, particularly HF. These findings highlight the importance of cardiovascular assessment and monitoring in this setting.