Abstract Body (Do not enter title and authors here): Background:
Transthyretin amyloid cardiomyopathy (ATTR-CM) is associated with high risk for heart failure (HF) hospitalization. However, little is known regarding post-discharge outcomes and healthcare costs for patients with underlying ATTR-CM, as compared with the general HF population.

Methods:
We analyzed Medicare beneficiaries hospitalized for HF in the Get With The Guidelines-Heart Failure (GWTG-HF) registry and discharged alive from January 1, 2021, to June 30, 2023. Patients were compared according to the presence or absence of an ATTR-CM diagnosis, as documented in the GWTG-HF case report form. All-cause mortality, HF readmission, and all-cause readmission over 1-year post-discharge were assessed in unadjusted and adjusted risk models. Inpatient, outpatient (excluding medications), and total per-patient healthcare costs over the 1-year post-discharge were calculated from payments made by Medicare.

Results:
Among 102,160 patients across 563 US hospitals, 190 (0.2%) carried a diagnosis of ATTR-CM. Compared to those without ATTR-CM, patients with an ATTR-CM diagnosis were older (82 [76–87] vs 80 [73–87] years), more likely to be male (68.9% vs 47.0%), and had lower ejection fraction (45 [30–57] vs 53 [35–60]%). Patients with ATTR-CM were significantly more likely to be discharged on a mineralocorticoid receptor antagonist (29.5% vs 20.4%) and SGLT2 inhibitor (21.6% vs 14.1%), and significantly less likely to be discharged on a beta-blocker (52.1% vs 77.6%). After adjustment, ATTR-CM was associated with higher risk of 1-year HF readmission (36.8% vs. 28.2%; HR 1.28, 95% CI 1.01–1.61, p=0.04), but not all-cause mortality (40.0% vs. 34.2%; HR 1.08, 95% CI 0.88–1.31, p=0.47) or all-cause readmission (64.2% vs. 63.4%; HR 0.98, 95% CI 0.83–1.17, p=0.85) (Table 1). Mean 1-year total per-patient Medicare costs were higher among patients with ATTR-CM than those without ($60,373 vs $50,247; p=0.04), primarily driven by significant differences in outpatient costs ($20,866 vs $16,358]; p=0.03) (Table 2).

Conclusion:
Among older adults hospitalized for HF in the US, patients with underlying ATTR-CM experience similarly high rates of post-discharge mortality, but face greater risks of HF readmission and accrue higher post-discharge healthcare costs. These findings highlight a disproportionate clinical and economic burden of ATTR-CM compared with the general HF population, further supporting the need for earlier identification and tailored care strategies.