Background: Myocardial infarction (MI) mortality varies substantially within high-income countries. There is limited guidance on what interventions – primary and secondary prevention and/or improving care pathways and quality – can reduce and equalise MI mortality. Our aim
was to understand the contribution of incidence (event rate), pre-hospital deaths and hospital case-fatality, to how MI mortality varies within England.
Methods: We used linked data on hospitalisation and deaths from 2015-2018 with geographical identifiers to estimate MI death and event rates, pre-hospital deaths and hospital case fatality for men and women aged 45 years and older in 326 districts in England. Data were analysed in a Bayesian spatial model that accounted for similarities and differences in
spatial patterns of fatal and non-fatal MI.
Results: The 99th to 1st percentile ratio of age-standardised MI death rate was 2.63 (95% credible interval 2.45-2.83) in women and 2.56 (2.37-2.76) in men across districts, with death rate highest in north of England. The main contributor to this variation was MI event rate, with a 99th to 1st percentile ratio of 2.55 (2.39-2.72) (women) and 2.17 (2.08-2.27) (men) across districts. Pre-hospital mortality was greater than hospital case fatality in every district. Prehospital mortality had a 99th to 1st percentile ratio 1.60 (1.50-1.70) in women and 1.75 (1.66-
1.86) in men across districts and made a greater contribution to case-fatality variation than
hospital case fatality which had a 99th to 1st percentile ratio of 1.39 (1.29-1.49) (women) and
1.49 (1.39-1.60) (men). The contribution of case fatality to variation in deaths across districts
was largest in middle ages. Pre-hospital mortality was slightly higher in men than women in
most districts and age groups, whereas hospital case fatality was higher in women in virtually
all districts at ages up to and including 65-74 years; after this age, it became similar between
the sexes.
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Interpretation: Most of the variation in MI death rate is due to variation in MI event rate, with
a smaller role for case fatality. The majority of variation in case fatality occurs before rather
than after hospital admission. Reducing subnational variations in MI mortality requires
interventions that reduce event rate and pre-hospital deaths.