Abstract Body (Do not enter title and authors here): Introduction: Chimeric antigen receptor T-cell (CAR-T) therapy has emerged as a breakthrough treatment for refractory hematologic malignancies. However, its cardiac risks and hemodynamic complications raise concerns for patients with heart failure (HF). The impact of HF on CAR-T–related inpatient outcomes remains unclear. This study leverages national inpatient data to evaluate how HF influences mortality, length of stay, and healthcare costs during CAR-T hospitalizations.

Methods: We conducted a retrospective analysis of the National Inpatient Sample (2017–2022), identifying adult hospitalizations involving CAR-T cell therapy using the relevant ICD-10-PCS code. Patients were stratified into two groups: those with and without heart failure. Outcomes included in-hospital mortality, length of stay, and total hospital charges. Survey-weighted multivariable logistic and linear regression models were used to assess associations, adjusting for demographics, comorbidities, and hospital-level factors.

Results: Among an estimated 32,640 nationally weighted CAR-T hospitalizations, approximately 931 patients (2.85%) had a diagnosis of heart failure (HF). Compared to those without HF, these patients were more frequently female (65.6% vs. 58.7%, p = 0.08) and White (75.8% vs. 64.9%, p = 0.013). HF patients were also significantly older (mean age 64.5 vs. 45.5 years, p < 0.001) and had a substantially higher comorbidity burden, with 97.8% having a Charlson Comorbidity Index ≥3 (p < 0.001). After adjustment for demographics, comorbidities, and hospital characteristics, HF was associated with a 3.68-fold higher odds of in-hospital mortality (95% CI: 1.75–7.74, p = 0.001). HF patients also experienced a more extended average hospital stay (19.4 vs. 10.8 days), with an adjusted increase of 5.96 days (95% CI: 2.67–9.25, p < 0.001), and higher total hospital charges ($1.15 million vs. $561,000), with an adjusted difference of $418,435 (95% CI: $227,767–$609,102, p < 0.001).

Conclusion: Heart failure is associated with significantly worse inpatient outcomes among patients undergoing CAR-T therapy, including higher mortality, longer hospital stays, and increased healthcare costs. These findings underscore the importance of incorporating cardiac risk assessment into the clinical evaluation of CAR-T candidates. Further validation through large-scale prospective studies is essential to confirm these associations and support evidence-based treatment strategies.