Abstract Body (Do not enter title and authors here): Introduction: Cardiomyopathy (CM) and myocarditis rank as the fifth leading cause of death and disability in G20 countries amongst all cardiovascular disease related (CVD) deaths. Despite their escalating burden, there is a notable lack of consistent data across these nations. This study is the first to estimate the burden of these cardiac conditions over the last three decades, including the initial two years of the COVID-19 pandemic, highlighting the urgent need for improved surveillance and specific healthcare strategies to manage these critical health issues.

Method: We estimated incidence, prevalence, deaths, disability-adjusted life years (DALYs), years lived with disability (YLDs) due to CM and myocarditis by age, sex, year and location across the G20 countries from 1990-2021 using global burden of disease 2021 methodology.

Results: From 1990 to 2021, the total percentage change (TPC) in prevalence counts increased by 64% (95% Uncertainty Interval: 53% to 75%), incidence by 57% (47% to 68%), and deaths by 37% (26% to 49%). Japan had the highest age-standardized incidence rate (ASIR) at 19.84 (16.38-24.21) cases per 100,000, closely followed by Sweden at 19.74 cases per 100,000. The highest mortality rate (ASMR) was observed in Latvia at 27.95 (23.89-31.99) cases per 100,000, with Russia following at 26.3 cases per 100,000 in 2021. Poland recorded the highest YLD rate (ASYLDR) at 16.13 (11.05-22.86), with Sweden next at 15.67 per 100,000 in 2021. The highest incidence occurred in the 70-74 age group with 76,173 cases (46,415-113,840), with the most deaths in the 80-84 age group at 31,289 (27,390-33,741), and the highest DALYs in the 55-59 age group at 750,723 (680,540-814,890) in 2021. Regarding gender, the TPC in incidence for males was 55% compared to 61% for females, in deaths 57% for males versus 16% for females, and in YLDs 67% for males versus 54% for females from 1990 to 2021.

Conclusion: Deaths due to CM and myocarditis accounted for 2.04% of all CVD deaths in G20 countries in 2021. The increasing burden highlights the need of proactive initiatives, including tailored health education and advanced screening programs. It should be prioritized to address the needs of the most affected demographics and regions. Integrating technology and cross-border healthcare collaborations could play a pivotal role in mitigating the impact of this condition and enhancing overall public health resilience.