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/km(2), n = 69 797; medium: 951.7–4729.7/km(2), n = 69 750; high: ≥4729.7/km(2), 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/km(2); 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/km(2); 95% CI, 0.973–0.992; P < 0.001; adjusted OR, 0.980 per 1000/km(2); 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.