Outcome of Percutaneous Coronary Intervention in Relation to the Institutional Volume of Coronary Artery Bypass Surgery

BACKGROUND: Percutaneous coronary intervention (PCI) is performed in a wide range of institutions. We sought to assess the relationship between coronary artery bypass grafting (CABG) volume relative to PCI volume and clinical outcome using nationally representative PCI and CABG registries in Japan. METHODS: This was a collaborative, registry-based cohort study enrolling patients undergoing percutaneous coronary intervention in 2013-2014 using Japanese nationwide registry (J-PCI) with follow up until discharge. The absolute volume of CABG for each hospital was calculated using additional data from Japan CardioVascular Surgery Database (JCVSD). Patients undergoing their first PCI registered in the registry (N = 220,934), at 943 facilities were studied. Main outcomes were in-hospital mortality, and incidence of composite of in-hospital death and postprocedural complications. RESULTS: Among the 220,934 patients, 162,411 were men, with a mean age of 69.7 (SD 11.6) years. Patients underwent PCI at hospitals with varying CABG volume: The overall in-hospital mortality and composite event rate for PCI patients was 0.9% and 2.4%, respectively. CABG volume was associated with the in-hospital mortality of PCI at facilities performing less than 200 PCIs per year, but not at facilities performing 200 or more. Similarly, in-hospital mortality or complication was associated with PCI volume <200 only if no CABG is done at the facility. The result remained largely consistent in subgroup of patients presenting with acute coronary syndrome or even after excluding these institutions with extremely low number of PCI (<50 cases/year) or CABG (<15 cases / year). CONCLUSIONS: In a nationwide registry-based analysis, the surgical volume was associated with patients' clinical outcome after PCI, when limited number of PCIs were performed at the facility.