Background Little is known about geographic variation in acute myocardial infarction (AMI) mortality within fast-developing megacities and whether changes in health care accessibility correspond to changes in AMI mortality at the small-area level. Methods and Results We included data of 94 106 AMI deaths during 2007 to 2018 from the Beijing Cardiovascular Disease Surveillance System in this ecological study. We estimated AMI mortality for 307 townships during consecutive 3-year periods with a Bayesian spatial model. Township-level health care accessibility was measured using an enhanced 2-step floating catchment area method. Linear regression models were used to examine the association between health care accessibility and AMI mortality. During 2007 to 2018, median AMI mortality in townships declined from 86.3 (95% CI, 34.2-173.8) to 49.4 (95% CI, 30.5-73.7) per 100 000 population. The decrease in AMI mortality was larger in townships where health care accessibility increased more rapidly. Geographic inequality, defined as the ratio of the 90th to 10th percentile of mortality in townships, increased from 3.4 to 3.8. In total, 86.3% (265/307) of townships had an increase in health care accessibility. Each 10% increase in health care accessibility was associated with a -0.71% (95% CI, -1.08% to -0.33%) change in AMI mortality. Conclusions Geographic disparities in AMI mortality among Beijing townships are large and increasing. A relative increase in township-level health care accessibility is associated with a relative decrease in AMI mortality. Targeted improvement of health care accessibility in areas with high AMI mortality may help reduce AMI burden and improve its geographic inequality in megacities.
Keywords: acute myocardial infarction; geographic variation; health care accessibility; mortality.