Acute Myocardial Infarction and Daylight Saving Time: A Large Registry Analysis

Article Impact Level: HIGH
Data Quality: STRONG
Summary of JAMA Network Open, 8(9), e2530442. https://doi.org/10.1001/jamanetworkopen.2025.30442
Dr Jennifer A. Rymer et al.

Points

Researchers examined whether daylight saving time influences acute myocardial infarction incidence or patient outcomes.
A substantial cross-sectional study analyzed data from 168,870 patients in a comprehensive registry.
No statistically significant differences in acute myocardial infarction rates were observed during daylight saving time weeks.
Furthermore, in-hospital mortality and stroke rates remained similar across all comparison periods.
These results indicate no significant association between daylight saving time and heart attack occurrence or severity.

Summary

This cross-sectional study investigated the association of daylight saving time (DST) with the incidence and outcomes of acute myocardial infarction (AMI). Using data from the Chest Pain MI Registry from 2013 to 2022, the final cohort included 168,870 patients across 1124 hospitals. The study compared AMI incidence and in-hospital outcomes (mortality and stroke) during the week of DST transitions (spring and fall) with the weeks immediately before and after these transitions. Patient demographics, including a median age of 65 years (IQR 56-75) and 33.8% female representation, were similar across the comparison groups for both spring and fall DST periods.

The researchers found no significant difference in the incidence of AMI when comparing spring DST weeks with the week prior or after, nor for fall DST weeks against their respective preceding or succeeding weeks. Specifically, during spring DST, 28,678 patients (17.0%) presented with AMI, compared to 28,596 (16.9%) the week before and 28,169 (16.7%) the week after. Similarly, for fall DST, 27,942 patients (16.5%) presented with AMI, versus 27,365 (16.2%) the week before and 28,120 (16.7%) the week after. These numerical comparisons consistently showed no statistically significant variations in AMI incidence ratios.

Furthermore, the study observed no significant differences in adjusted in-hospital outcomes, including mortality and stroke, for the weeks around either spring or fall DST. This large-scale analysis, encompassing a contemporary dataset, contradicts some older, smaller studies that suggested an increased AMI incidence following DST transitions. The findings indicate that the time changes associated with DST do not have a significant association with the incidence or clinical outcomes of patients presenting with AMI.

Link to the article: https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2838653

References

Rymer, J. A., Li, S., Chiswell, K., Kansal, A., Nanna, M. G., Gutierrez, J. A., Feldman, D. N., Rao, S. V., & Swaminathan, R. V. (2025). Daylight savings time and acute myocardial infarction. JAMA Network Open, 8(9), e2530442. https://doi.org/10.1001/jamanetworkopen.2025.30442