Age and sex differences in the circadian distribution of myocardial infarction and impact on outcomes
S Heanue, W Hong, K Lambrakis, K Tsigaridis, L Scanlon, S Leong, R Rebecca, A Brennan, D Dinh, N Nerlekar, R Gooley, D Chew, A LinAbstract
Background
The circadian pattern of acute myocardial infarction (MI) onset is associated with subsequent clinical outcomes. We sought to examine the impact of age and sex on the association between time of symptom onset (TSO) in MI and 30-day mortality following percutaneous coronary intervention (PCI).
Methods
Within the statewide Victorian Cardiac Outcomes Registry in Australia, we identified patients with MI who had documented TSO and underwent PCI between 2013-2023. Patients were stratified by age < or ≥ 65 years. TSO as an outcome was summarized as circular means ± circular standard deviations and compared using circular-linear regression. TSO as a predictor was transformed using a periodic cubic B-spline with boundary knots at 00:00 and 24:00 and internal knots at 06:00, 12:00, and 18:00.
Results
The final study population comprised 26,459 patients (77.4% male; mean age 63.8 ± 12.5 years; 58.1% with ST-elevation MI presentation). Overall, 96.0% patients underwent successful PCI during the index admission. The mean TSO occurred later in patients aged <65 years compared to those aged ≥65 years (12:07 ± 6:32 vs. 11:43 ± 6:25; p <0.001). Mortality at 30 days varied significantly by TSO in patients aged <65 years (OR 0.32, 95% confidence interval 0.14-0.71 at 12:00 compared to midnight), following adjustment for age, sex, diabetes, ST-elevation MI presentation, and history of coronary revascularisation. The same association was not observed in patients aged ≥65 years. In both age groups, males experienced an earlier TSO than females (p<0.001), however the relationship between sex and 30-day mortality did not differ significantly by TSO.
Conclusion
TSO differs according to age and sex among patients presenting with MI, and is independently associated with subsequent 30-day mortality following PCI in patients aged <65 years. This highlights potential differences in the effect of the circadian system on MI, and may in future help inform risk stratification and resourcing.