Figure 4. Hazard ratios (HRs) of 1‐year all‐cause mortality between hospital groups, categorized into llow‐, medium‐, and high‐volume, according to the annual institutional primary percutaneous coronary intervention (PCI) volume.

A indicates adjusted for sex, TIMI (Thrombolysis in Myocardial Infarction) risk score, insurance coverage, living in poverty, family history, smoking status, culprit lesion in proximal left anterior descending artery, number of years catheterization laboratory was performing percutaneous coronary interventions, and year of enrollment. U, unadjusted.