Population Density Analysis of Percutaneous Coronary Intervention for ST-Segment-Elevation Myocardial Infarction in Japan

Background Despite recent progress in the treatment of ST-segment-elevation myocardial infarction, data on geographic disparities application of the evidence-based therapy remain limited. Methods and Results The J-PCI (Japanese Percutaneous Coronary Intervention) registry is a nationwide registry to assure the quality of delivered care. Between January 2014 and December 2018, 209 521 patients underwent percutaneous coronary intervention for ST-segment-elevation myocardial infarction in 1126 institutions. The patients were divided into tertiles according to the population density (PD) of the percutaneous coronary intervention institution location (low: <951.7/km², n = 69 797; medium: 951.7-4729.7/km², n = 69 750; high: ≥4729.7/km², n = 69 974). Patients treated in high PD administrative districts were younger and more likely to be male. No significant correlation was observed between PD and door-to-balloon time (regression coefficients: 0.036 per 1000 people/km²; 95% CI, -0.232 to 0.304; P = 0.79). Patients treated in low-PD areas had higher crude in-hospital mortality rates than those treated in high-PD areas (low: 2.89%; medium: 2.60%; high: 2.38%; P < 0.001); PD and in-hospital mortality had a significantly inverse association, before and after adjusting for baseline characteristics (crude odds ratio [OR], 0.983 per 1000/km²; 95% CI, 0.973-0.992; P < 0.001; adjusted OR, 0.980 per 1000/km²; 95% CI, 0.964-0.996; P = 0.01, respectively). Higher-PD districts had more operators per institution (low: 6; interquartile range, 3-10; medium: 7; IQR, 3-13; high: 8; IQR, 5-13; P < 0.001), suggesting an inverse association with in-hospital mortality (OR, 0.992; 95% CI, 0.986-0.999; P = 0.03). Conclusions Geographic inequality was observed in in-hospital mortality of patients with ST-segment-elevation myocardial infarction who underwent percutaneous coronary intervention. Variation in the number of operators per institution, rather than traditional quality indicators (eg, door-to-balloon time) might explain the difference in in-hospital mortality.