Abstract Body (Do not enter title and authors here):

Background
Myocarditis remains an underrecognized contributor to cardiac morbidity and mortality globally. There is limited understanding of how myocarditis trends have evolved over time in regions such as South Asia compared to high-income countries like the United States.
Methods
We used data from the Global Burden of Disease 2021 Study to assess age-standardized mortality rates (ASMR) and age-standardized incidence rates (ASIR) of myocarditis in South Asia and the United States between 1990 and 2021. Joinpoint regression with four fixed segments (1990–1997, 1997–2001, 2001–2010, 2010–2021) was applied to evaluate Annual Percent Change (APC) and its statistical significance within each segment.
Results
From 1990 to 2021, the age-standardized mortality rate (ASMR) for myocarditis in South Asia declined from 0.36 to 0.29 deaths per 100,000. The most pronounced decreases occurred during 1997–2001 (APC −2.37%) and 2010–2021 (APC −1.42%). In the United States, ASMR declined from 0.29 to 0.21, with significant reductions after 2001 (APC −2.84%) and again post-2010 (APC −3.07%). The ASMR remained lower in the United States than in South Asia throughout the study period.
The age-standardized incidence rate (ASIR) in South Asia remained stable, changing from 16.44 to 16.34 per 100,000, with all annual percentage changes (APCs) non-significant. In the United States, ASIR declined from 19.42 to 18.31 per 100,000. The trend in the U.S. showed a rise prior to 1997 (APC +0.81%), a decline after 2001 (APC −1.86%), and an increase again after 2010 (APC +1.69%). Absolute ASIR values were consistently higher in the United States than in South Asia over the study period.
Conclusion
Despite relatively low absolute burden, myocarditis trends reveal persistent regional disparities. South Asia shows minimal improvement in both incidence and mortality, while the United States experienced statistically significant declines in mortality and a late rebound in incidence. These findings highlight the need for improved myocarditis surveillance and cardiovascular infrastructure in developing regions.