Analysis of the institutional volume-outcome relations for balloon angioplasty and stenting in the stent era in California

Background Coronary artery stenting has become the predominant form of percutaneous coronary intervention. However, it is not clear whether a better outcome is conferred by stent placement in high-volume, more experienced centers as has been shown with balloon angioplasty. Furthermore, as stent procedures become more common, balloon angioplasty becomes less frequent. Thus, we separately analyzed the outcomes after coronary angioplasty and stenting in a large, unselected population to determine the effect of annual institutional angioplasty or stent volume on in-hospital outcomes after balloon angioplasty or stenting. Methods The California Office of Statewide Health Planning and Development database was queried to obtain discharge data on all patients in 1997 treated with percutaneous transluminal coronary angioplasty (PTCA) or a stent procedure. Hospitals were divided into low-volume (<200 procedures), intermediate-volume (200 to 400 procedures), and high-volume (>400 procedures) institutions as a function of their 1997 PTCA or stent volumes to assess the effect of volume on outcome. Results There were 44,276 percutaneous revascularization procedures performed in California in 1997, of which 57% involved coronary stent placement. Mortality rates after PTCA were 2.6%, 1.9%, and 1.4% in low-, intermediate- and high-volume PTCA hospitals, respectively (P <.001). The need for same-day coronary artery bypass grafting (CABG) after PTCA was 2.4%, 2.1%, and 1.2% in low-, intermediate- and high-volume PTCA hospitals, respectively (P <.001). Mortality rates after stent placement were 1.6%, 1.5%, and 1.1% in low-, intermediate-, and high-volume stent hospitals, respectively (P =.022). The need for same-day CABG after stent placement was 1.1%, 1.2%, and 0.8% in low-, intermediate-, and high-volume stent hospitals, respectively (P =.014). Conclusions Short-term results of balloon angioplasty and stent procedures are improved when performed in high-volume hospitals.