Abstract Body (Do not enter title and authors here): Introduction: Dilated cardiomyopathy (DCM) is associated with a significant mortality risk, with untreated cases showing a five-year survival rate of just 50%. However, there is a scarcity of data on how DCM-related mortality rates have changed over time.

Goals: How have temporal trends and demographic disparities in DCM mortality evolved in the United States over time?

Methods: Mortality/demographic data (i.e. sex, race, ethnicity, and area of residence) in adults in the US spanning from 1999-2020 were sourced from the CDC-WONDER database, using ICD-10 code I42.0. Age-adjusted mortality rates (AAMR) per 1,000,000 population were standardized to the 2000 US population. Temporal trends in mortality were assessed using log-linear regression, with results expressed as the average annual percentage change (AAPC).

Results: A total of 168,702 DCM deaths were recorded between 1999-2020. DCM-related AAMR declined from 34.00 [95% CI, 33.31-34.69] in 1999 to 17.17 [16.74-17.59] in 2020, with AAPC -3.47%, p<0.001. Higher mortality was observed in males (AAMR 33.94 [33.74-34.15]) than females (AAMR 14.68 [14.56-14.80]), in non-Hispanic populations (AAMR 24.06 [23.94-24.18]) compared to their Hispanic counterparts (AAMR 16.68 [16.35-17.01]), and in rural regions (AAMR 23.31 [23.03-23.59]) compared to urban regions (AAMR 23.31 [23.19-23.44]). Black populations (AAMR 41.89 [41.42-42.36]) and residents of the Midwestern US region (AAMR 26.14 [25.89-26.39]) experienced the highest mortality rates.

Conclusions: DCM-related mortality halved between 1999 and 2020. However, the burden of mortality disproportionately affected males and Black populations. Further research is essential to uncover the underlying factors contributing to these disparities.