SNOWMASS, COLO. – Current American Heart Association consensus recommendations for noninvasive testing of women with suspected ischemic heart disease utilize a novel and simplified approach to pretest risk stratification.
The writing committee’s thinking was that a new risk assessment method specific to symptomatic women was needed. Conventional risk scores, such as the Framingham and American College of Cardiology/AHA atherosclerotic cardiovascular disease risk calculator, are weighted for risk evaluation in the general population of asymptomatic men and women, committee cochair Dr. Jennifer H. Mieres explained at the Annual Cardiovascular Conference at Snowmass.
The pretest risk assessment strategy for ischemic heart disease (IHD) described in the AHA consensus statement (Circulation. 2014 Jul 22;130:350-79) is applicable only in women who present with chest pain symptoms or an ischemic equivalent such as excessive shortness of breath not attributable to underlying pulmonary disease. It’s designed to avoid overuse of costly noninvasive and invasive diagnostic testing, which has become common in concert with increasing physician awareness that the pattern of symptom presentation is broader in women than men with IHD.
Given the epidemiologic evidence that coronary heart disease tends to occur a decade later in women than men, the female-specific risk assessment method utilizes age as its starting point. In general, women who present with symptoms suggestive of IHD in their 50s are classified as low risk. Those in their 60s are deemed intermediate risk. And symptomatic women in their 70s are categorized as high risk. A patient gets bumped up one risk category if she has multiple cardiac risk factors or functional disability, according to Dr. Mieres, professor of cardiology and population health at Hofstra University in Hempstead, N.Y.
Functional disability is defined as inability to perform activities of daily living or as a limited exercise capacity estimated at less than 5 metabolic equivalents (METs) using the Duke Activities Status Index (DASI), a validated brief 12-item questionnaire suitable for patients to complete in the waiting room.
A symptomatic woman’s baseline fitness level is important for a couple of reasons. If she can’t perform basic activities of daily living or do more than 5 METs of exercise then the exercise treadmill test is not the initial diagnostic test of choice because she won’t be able to achieve maximum stress.
Plus, the landmark Women’s Ischemia Syndrome Evaluation (WISE) study showed that a symptomatic woman’s baseline fitness level is a powerful predictor of her prognosis: Participants who had an estimated exercise capacity of 4.7 METs or less based upon their DASI score had a 3.7-fold greater risk of death or nonfatal MI during follow-up did than those with a DASI score of 10 METs or more. Those with a DASI score of 4.8-7.4 METs were 2.1-fold more likely to experience death or MI, and women with an estimated exercise capacity of 7.5-9.9 METs based upon DASI were at 1.9-fold increased risk of death or MI, compared with those having a DASI score of at least 10 METs (J Am Coll Cardiol. 2006 Feb 7;47[3 Suppl]:S36-43).
In addition, the women’s IHD risk evaluation utilizes several high-risk equivalents which automatically move a symptomatic woman into the high-risk category regardless of her age. These are peripheral artery disease, longstanding poorly controlled diabetes, and a history of cerebrovascular accident, Dr. Mieres continued.
She stressed that most low-risk symptomatic women are not candidates for diagnostic testing. The exercise treadmill test is the first-line diagnostic test for women at intermediate risk for IHD who are functionally capable and have a normal resting ECG.
Stress imaging studies are reserved for intermediate- and high-risk women with resting ST-segment abnormalities, inability to exercise adequately, or an indeterminate exercise treadmill test.
Stress echocardiography gets a class I recommendation in these situations. So does stress myocardial perfusion imaging with SPECT or PET except in premenopausal women, where concerns about radiation exposure dictate that stress echo or stress cardiac magnetic resonance imaging is preferable.
Otherwise, stress cardiac magnetic resonance gets a class IIb – “may be reasonable” – recommendation as an initial imaging test in these situations.
Coronary artery calcium measurement via CT angiography gets a class IIb recommendation in intermediate-risk symptomatic women. This imaging method is unique in that it not only provides accurate information about the obstructive burden of CAD, but it measures the nonobstructive burden as well. That’s particularly important in women because they have a greater burden of nonobstructive CAD, defined as 1%-49% stenosis, than do men. Women with stress test abnormalities and nonobstructive CAD are no longer defined as having a false-positive test, as was traditionally the case; instead, their test is categorized as abnormal because the WISE study has shown they are at elevated IHD risk, Dr. Mieres said.