Better selection criteria needed for patients with stable angina who undergo coronary angiograms: study
New research by the Institute for Clinical Evaluative Sciences (ICES) and Cardiac Care Network of Ontario (CCN), shows 41.9 per cent of patients with a diagnosis of ‘stable angina’ had a normal coronary angiogram. While some coronary angiograms are expected to be normal, it is important that this proportion be minimized, given the invasive nature of angiography and the associated risk and significant health care costs.
“These findings illustrate that the current approach to selecting patients for coronary angiograms isn’t working optimally. In this study, we identified certain characteristics that can help predict when an angiogram will be normal; paying attention to these predictors can help to better select patients in the future,” says senior author and ICES Senior Scientist Dr. Jack Tu, who is also a cardiologist at Sunnybrook Schulich Heart Centre. “It turns out that many patients with chest pain who are thought to have angina, actually have some other cause for their chest pain.”
Coronary angiography plays an integral role in the diagnosis and management of patients with coronary artery disease (CAD) and is the standard test for the identification of CAD. However, it is associated with a small risk of serious complications estimated at 1 per cent and vascular complications at 2 to 4 per cent.
Stable angina patients represent approximately one out of every 3 patients undergoing angiogram in Ontario.
The study, published in American Heart Journal, examined 2,718 patients undergoing an index cardiac catheterization for an indication of stable angina between April 2006 and March 2007 at one of 17 cardiac hospitals in Ontario and found:
- Overall, 41.9 per cent of patients with stable angina had a normal catheterization.
- The rate of normal angiograms studied varied from 18.4 per cent to 76.9 per cent across hospitals and was more common in community compared with academic settings (47.1 vs. 35.4 per cent).
“The wide variation in Ontario in the frequency of normal angiograms in patients with stable angina suggests that there are opportunities to improve case selection. Female gender, absence of traditional cardiac risk factors, and lack of typical angina symptoms are all associated with a higher rate of normal results among stable patients,” says Dr. Eric A. Cohen, Deputy Head of the Schulich Heart Program, Sunnybrook Health Sciences Centre, and co-lead of the project.
The authors stress that the study also highlights the need to develop better non-invasive methods (e.g, novel biomarkers, newer imaging techniques such as CT Scans) to identify those patients who are more likely to have abnormal angiograms.
The authors would also stress that their results do not apply to patients having an angiogram for a diagnosis of a ‘heart attack’, where the proportion of normal angiograms is very low.
The study “Predictors of normal coronary arteries at coronary angiography” is in the current issue of American Heart Journal.
Authors: Kevin Levitt, Helen Guo, Harindra C. Wijeysundera, Dennis T. Ko, Madhu K. Natarajan, Christopher M. Feindel, Kori Kingsbury, Eric A. Cohen, and Jack V. Tu.
ICES is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of health care issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting health care needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy.
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The Cardiac Care Network of Ontario (CCN) is a network of 18 member hospitals providing cardiac services in Ontario. In addition, CCN serves an advisory role on matters pertaining to cardiovascular care, and is a system resource for patients and families, hospitals, Local Health Integration Networks and other stakeholders of the health care system in Ontario. In addition to helping plan, coordinate, implement and evaluate cardiovascular care in Ontario, CCN is responsible for developing, maintaining and reporting on the provincial cardiac wait list registry for all patients waiting for selected adult advanced cardiac procedures in Ontario. In the role of monitoring and enhancing quality of cardiac services in Ontario, CCN develops strategies, based on best practices, to better manage cardiovascular disease across the continuum of care, including strategies to prevent acute hospital readmissions, decrease demand on emergency departments and decrease the need for initial and repeat procedures. The Cardiac Care Network of Ontario is funded by the Ontario Ministry of Health and Long-Term Care.
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