A look at ACP's guideline on managing chronic angina
From the September ACP Observer, copyright © 2004 by the American College of Physicians.
By Phyllis Maguire
For internists, managing patients with chronic stable angina and evaluating their risk of coronary artery disease is a common—and high-stakes—problem. With failure to diagnose heart disease a major reason why internists are sued, it's important to promptly evaluate high-risk patients.
In 1999, ACP collaborated with the American College of Cardiology and the American Heart Association to produce a set of chronic stable angina guidelines that were updated in 2002. Those guidelines served as background for new ACP guidelines geared to helping general internists evaluate and treat chronic stable angina.
The first ACP guideline, which addressed diagnosis and risk stratification, was published this summer in the July 6 issue of Annals of Internal Medicine. A second guideline on pharmacologic therapy and follow-up will be published later this year.
The guideline addresses a growing problem for internists: asymptomatic patients
The guideline, summarizing ACC/AHA's updated findings, contains a new algorithm to evaluate suspected coronary artery disease. It also includes a testing algorithm to help physicians decide which diagnostic test to use for individual patients.
ACP Observer recently spoke with Douglas K. Owens, ACP Member, about the diagnosis and risk stratification guideline. Dr. Owens, a general internist with the VA Palo Alto Health Care System in Palo Alto, Calif., and an associate professor of medicine and health research and policy at Stanford University, is a member of ACP's Clinical Efficacy Assessment Subcommittee, which developed the new chronic stable angina guideline.
Q: The guideline recommends different diagnostic tests to use for different patient populations. However, computed tomography scanning for coronary calcification is not recommended.
A: The ACC/AHA reviewed the primary evidence and felt it couldn't recommend it because there is not sufficient evidence to support its use. As guidelines are updated, if there is any new evidence about the usefulness of CT, it will be reviewed.
Q: The guideline strongly recommends exercise echocardiography (ECG) for symptomatic patients who can exercise and are not taking digoxin. Did the committee feel exercise ECG is underutilized?
A: We found that some primary care physicians go right to sophisticated imaging studies. When the ACC/AHA reviewed the evidence, it found good evidence for the value of exercise treadmills, particularly the Duke Treadmill Score. There are many different kinds of scores out there, but there is good evidence that the Duke score performs well in stratifying patients' risk of clinically significant coronary artery disease.
For patients who can't exercise or who have left bundle-branch block or electronically paced ventricular rhythm, the guideline goes through a series of specific recommendations on which tests to use, such as perfusion imaging.
Q: Did the committee find confusion among general internists about which tests were appropriate for different patient groups?
A: The order or sequence of choosing tests—deciding which test is best for which patients—is a source of confusion because there are so many to choose from.
The algorithm we've included gives physicians a systematic approach to help them make that testing choice.
Q: These were the first ACC/AHA guidelines to include recommendations for asymptomatic patients. Why did the panel think asymptomatic patients needed to be addressed?
A: Increasingly, asymptomatic patients are having electron beam or ultrafast CT scanning and saying, "Here's my scan and it shows coronary calcium. Now what should I do?"
The recommendations help physicians approach risk stratification in those patients by going through the same algorithm: discussing risk factors, estimating their probability of coronary artery disease, taking the same approach to testing if the physician and patient think further testing is warranted.
The recommendations for asymptomatic patients are unusual in that they're based on expert opinion, which we typically don't include. But we felt this was a growing problem for internists, and there is very little evidence on asymptomatic patients.
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