Acute Myocardial Infarction Mortality in Young Adults in Brazil: Divergent Trends by Age, Sex, and Region, 2000-2025

BackgroundAcute myocardial infarction (AMI) mortality has declined in Brazil, but the national figure is driven by older adults.Whether young adults have shared in that decline has not been examined. MethodsWe analyzed all deaths with AMI as the underlying cause (International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) I21-I23) among individuals aged 20-39 years in the Brazilian Mortality Information System from 2000 to 2025.Rates were directly standardized by age and sex to the resident population enumerated in the 2022 Brazilian Demographic Census.Trends were estimated using segmented weighted log-linear (joinpoint) regression of the standardized rate, with 0-2 joinpoints selected using the Bayesian information criterion, stratified by sex, macroregion, and five-year age band.Reporting follows the REporting of studies Conducted using Observational Routinely-collected health Data (RECORD) statement. ResultsThere were 59,486 deaths.The standardized rate was 4.00 per 100,000 in 2000 and 3.76 in 2025, with no net change (average annual percent change (AAPC), -0.23%; 95% CI, -0.50 to +0.04).Joinpoints occurred in 2005 and 2009: the rate declined through 2005 (annual percent change (APC), -2.64%; 95% CI, -4.33 to -0.92), rose through 2009 (+1.96%; 95% CI, +0.33 to +3.62), and then remained stable (-0.01%; 95% CI, -0.37 to +0.34).This stable national trend reflected opposing movements.Mortality rose among individuals aged 20-24 years (+3.21%;95% CI, +2.41 to +4.01) and 25-29 years (+1.73%;95% CI, +1.39 to +2.08) but fell among those aged 35-39 years (-0.73%;95% CI, -0.99 to -0.46), narrowing the rate ratio for individuals aged 35-39 vs. 20-24 years from 13.1 to 6.3.Rates fell in women (-0.57%; 95% CI, -0.86 to -0.28) but not in men, widening the male-to-female ratio from 2.4 to 3.1.Regional trends ranged from -2.62% per year in the South to +1.88% in the North, reversing the regional rank order.Neither the choice of standard population nor inference robust to serial correlation altered any principal finding.Redistribution of ill-defined and nonspecific cause-ofdeath codes preserved the national, age, and regional patterns but eliminated the rise in the Northeast and the statistical significance of the small positive slope in men. ConclusionsAMI mortality among young adults in Brazil stopped declining in the late 2000s.The stable national rate conceals a rising burden among adults younger than 30 years and an inverted regional gradient, neither of which is apparent in all-age surveillance.The widening sex gap points in the same direction but does not persist after correction for cause-of-death misclassification.