BACKGROUND: The regional variability of percutaneous coronary intervention (PCI) rates may be explained by variations in the medical treatment of stable coronary artery disease. We sought to determine whether greater regional use of antianginal medications in PCI patients is associated with lower regional rates of PCI. METHODS AND RESULTS: Using CathPCI Registry and Dartmouth Atlas data, we examined patients undergoing elective PCI for stable coronary artery disease from January 1, 2009, through March 31, 2011, and calculated rates of providing ≥ 2 antianginal medicines before PCI. We regressed the hospital referral region rates of PCI per 1000 Medicare enrollees in 2007 on the regions' rates of providing ≥ 2 antianginal medications before PCI. Among 300772 PCI procedures, 32.8%, 48.3%, 16.1%, and 2.8% of patients were on 0, 1, 2, or ≥ 3 antianginal medications, respectively. The median rate of providing ≥ 2 antianginal medications before PCI was 18.9%. Although substantial variability existed across hospital referral regions in providing ≥ 2 antianginal medications and in rates of PCI from the Dartmouth Atlas, there was no association between the rates of PCI in each hospital referral region and the rates of ≥ 2 antianginal medications before PCI (Spearman ρ, 0.0277; P=0.64). CONCLUSIONS: We found no association between the intensity of antianginal therapy and the use of PCI across hospital referral regions, despite the variability of both. Opportunities likely exist in many regions to increase the use of antianginal therapy before proceeding to elective PCI, and more research is needed to explain observed variations in care.