Cardiovascular mortality trends in the United States, 1999–2024: an interrupted time-series analysis

U.S. cardiovascular mortality rose during the COVID-19 pandemic. Whether the increase represented a lasting departure from the long-term decline remains uncertain. We analyzed annual U.S. age-adjusted mortality rates for circulatory diseases (ICD-10 I00–I99) from CDC WONDER, 1999–2024. We described observed trends and calculated year-specific differences between 2020 and 2024 rates and forecasts fitted through 2019. Interrupted time-series ARIMA models estimated model-specific intervention terms. We assessed alternative trends and intervention responses, pre-pandemic forecast performance, multiple-cause-of-death data, and sex-specific patterns. The national age-adjusted cardiovascular mortality rate rose from 214.6 deaths per 100,000 in 2019 to 233.3 in 2021, then declined to 212.9 in 2024. Observed rates exceeded the upper nominal 95% prediction limit of the 1999–2019 ARIMA forecast in 2020 and 2021. In 2024, the observed rate was 5.0 per 100,000 above that forecast but within its prediction interval; it was 1.4 below a damped-trend forecast fitted to 2010–2019. Pre-pandemic backtesting showed weak interval calibration for several forecasting models. The selected intervention model estimated a post-2020 Step coefficient of 28.12 per 100,000 (95% CI, 21.19–35.06), a model-specific parameter distinct from the annual forecast differences. A recovering response fit nearly as well as a permanent response in a separate model comparison. U.S. cardiovascular mortality increased in 2020–2021 and declined through 2024. The early increase exceeded the reference forecast’s nominal prediction limits, but estimates of later departures depended on the forecasting model. The available annual data cannot distinguish a permanent shift from gradual recovery.