Abstract Body (Do not enter title and authors here): Background: Primary malignant cardiac tumors (PMCT) pose a unique clinical challenge due to their rarity, limited treatment options, and aggressive disease course. The aim of this study is to understand clinical characteristics and survival rates based on initial presentation of patients admitted with PMCTs.

Methods: From 2016 to 2020, we employed the National Readmission Database to identify individuals ≥18 years of age who were initially admitted with a diagnosis of PMCT. Kaplan-Meier survival analysis was reported as hazard ratios to estimate survival rates. All statistical analyses were performed using Stata 18.0 software.

Results: We identified 1,646 patients with PMCTs (mean age 54.9 years, 52.2% female).The all-cause in-hospital mortality rate was 10.9% (n=180). Amongst surviving patients at index admission, overall 30-day readmission rate was 25.7%, while the 90-day readmission rate was 32.7% post the index admission. Heart failure, atrial fibrillation, and ventricular tachycardia/ventricular fibrillation were the leading causes of index hospitalization, 30-day and 90-day readmission (Table 1). When assessing survival rate based on the index admission, a significant difference was noted amongst patients based on their acute coronary syndrome (ACS) status; HR: 2.7 [1.01- 7.45], p=0.048. A trend for significance was observed based on atrial fibrillation (AF) status; HR: 1.5 [0.92- 2.6], p=0.096. There was no difference in survival rates amongst patients based on their HF status; HR: 1.07 [0.63- 1.81], p=0.811. A sub-analysis of patients with heart failure with preserved (HFpEF) and reduced ejection fraction (HFpEF) revealed similar results; HR: 0.5 [0.16- 1.59], p=0.239.

Conclusion: Patients with PMCTs have comparable survival rates despite variations in clinical presentations on index hospitalization. Elevated 30-day (25.7%) and 90-day (32.7%) readmission rates underscore the need for patient centered, pre-discharge management.