Volume-Outcome Relationships for Intra-Aortic Balloon Pump in Acute Myocardial Infarction

Background: Acute myocardial infarction (AMI) is a major scenario for the use of an intra-aortic balloon pump (IABP), particularly when complicated by cardiogenic shock, although the utilization of mechanical circulatory support devices varies widely per hospital. We evaluated the relationship, at the hospital level, between the volume of IABP use and mortality in AMI.Methods and Results: Using a Japanese nationwide administrative database, 26,490 patients with AMI undergoing primary percutaneous coronary intervention (PCI) from 154 hospitals were included in this study. The primary endpoint was the observed-to-predicted in-hospital mortality ratio. Predicted mortality per patient was calculated using baseline variables and averaged for each hospital. The associations among PCI volume for AMI, observed and predicted in-hospital mortality, and observed and predicted IABP use were assessed per hospital. Of 26,490 patients, 2,959 (11.2%) were treated with IABP and 1,283 (4.8%) died during hospitalization. The annualized number of uses of IABP per hospital in AMI was 4.5. In lower-volume primary PCI centers, IABP was more likely to be underused than expected, and the observed-to-predicted in-hospital mortality ratio was higher than in higher-volume centers.Conclusions: A lower annual number of IABP use was associated with an increased mortality risk at the hospital level, suggesting that IABP use can be an institutional quality indicator in the setting of AMI.