Abstract 11425: Clinical Determinants of Normal Coronary Angiograms in Ontario

Abstract

Introduction: Coronary angiography remains an integral diagnostic tool in the management of patients with suspected coronary artery disease. However, the clinical determinants and rates of normal angiograms in Ontario, Canada are unknown. Hypothesis: We tested the hypothesis that a significant proportion of patients undergoing cardiac catheterization for stable angina will have normal coronary anatomy and that there would be significant variation in the proportion of normal angiograms between academic and community centers.

Methods: We conducted a study using the Variation in Revascularization Practice in Ontario database of 2718 patients undergoing an index cardiac catheterization for a clinical indication of ‘stable angina’ between April, 2006 and March, 2007 at one of 17 hospitals in Ontario. We determined predictors of normal coronary anatomy and compared rates of patients with normal catheterizations across centers.

Results: Overall, the proportion of normal angiograms was 41.9%. However there was significant variation in this rate from 18.4% to 76.9% across hospitals and was more common in community hospitals compared to academic settings (47.1% vs 35.4%, p<.001). A multivariate model demonstrated female gender to be the strongest predictor of a normal angiogram (Table 1). In addition, atypical symptoms or no symptoms and the absence of diabetes, hyperlipidemia, smoking history, and peripheral vascular disease also were associated with higher rates of normal catheterization.

Conclusions: The absence of traditional cardiac risk factors, female gender, and lack of typical angina symptoms are all associated with a higher frequency of normal cardiac catheterizations. The wide variation in the frequency of normal angiograms across Ontario hospitals suggests there are opportunities to improve patient selection and decrease the frequency of normal angiograms in certain centers.