The WOMEN Study: What is the Optimal Method for Ischemia Evaluation in WomeN?

Coronary artery disease remains the leading cause of morbidity and mortality in women accounting for more than 250,000 deaths per year. While mortality rates have decreased significantly in men during the last several decades, there has been little change for women. Furthermore, despite the high prevalence of ischemic heart disease (IHD) in women, most clinical trials have focused on male cohorts, resulting in a lack of data for women. Their exclusion from clinical trials has been primarily due to the following: 1) child- bearing potential, 2) beyond the arbitrary age limits established for trials, 3) frequent concomitant or advanced disease, and 4) inhomogeneity within the study population.

Extrapolation of the published clinical trial data (predominately obtained in men) for women is controversial due to differences in epidemiology of heart disease in women. Treatment is often sought later in life and is usually accompanied by more advanced disease and co-morbidities, which therefore, impact survival. In addition, women more frequently have an absence of clinical symptoms or an atypical presentation, making the diagnosis of coronary artery disease (CAD) challenging. Furthermore, women may also have their first manifestation of CAD as sudden death or acute myocardial infarction. Therefore, there is a clear need for the early identification of IHD in women so that treatments may be employed prior to having an advanced state of disease and higher risk for unfavorable outcomes.

The optimal non-invasive test for evaluation of IHD in women is unknown. A number of different modalities have been employed including exercise ECG stress testing, 2-dimensional stress echocardiography, single photon emission computerized tomography (SPECT) myocardial perfusion imaging, and electron beam tomography. Additionally, the cohort of women for whom testing is performed is also ill defined.

The most recent AHA/ACC guidelines suggest that ECG stress testing should be the preferred approach. Supportive data for this recommendation are controversial, as many of the studies examining the diagnostic value of ECG stress testing were largely performed in small cohorts of women and are dated. These trials indicate that the diagnostic accuracy of stress testing is only fair (sensitivity=32-89%; specificity=41-68%). A recent meta-analysis in 3,874 women demonstrated modest sensitivity and specificity, 62% and 69% respectively, even after adjustment for referral bias (8). Published guidelines have also included a meta-analysis and confirmed a low level (sensitivity=33%) of detection of disease. Additionally, the high rate of false positives, as well as the inability to fully ascertain the extent of disease, therefore limits the potential value of ECG stress testing.

Even though exercise stress testing is supported by recent clinical guidelines, the addition of SPECT myocardial perfusion imaging has independent and incremental diagnostic and prognostic value. Improved diagnostic accuracy has also been noted with perfusion imaging and its ability to predict cardiac events in women is well established. Furthermore, recent data supports the cost-effectiveness of strategies that employ myocardial perfusion imaging in the assessment of women at risk for ICD.

The current AHA/ACC recommendations fail to take into account that women often have limited ability to complete maximal exercise, a problem that is likely due to their older age and more frequent co-morbidities as compared with men. This functional impairment may lead to a lack of ischemia provocation and/or indeterminate exercise testing results. Maximal predicted heart rate, oxygen consumption, and, more commonly, metabolic equivalents (METs) are measures to estimate physical work capacity. The Duke Activity Status Index (DASI) is a simple 12-item questionnaire that estimates peak oxygen consumption. The Duke Activity Status Index (DASI) questionnaire may identify patients who are likely to perform inadequate exercise, which amounts to nearly 40% of all women referred for exercise testing.

The optimal strategy for the evaluation of women with suspected ischemic heart disease is unknown and quite controversial. Several algorithms have been suggested for the evaluation of women with suspected CAD. A recent consensus paper from the American Society of Nuclear Cardiology suggested a strategy that employed perfusion imaging, but provided little evidence to support such a clinical strategy, such as with a prospective clinical trial. The focus of this investigation is to compare different strategies for the assessment of women at intermediate or high clinical risk for IHD and to do so on a prospective, randomized basis. This study is therefore focused on providing a high level of clinical evidence on which to base future recommendations and guidelines for the care of women with heart disease.

Inclusion criteria

• Women 60 years of age and older presenting for the evaluation of chest pain, or other anginal equivalent symptoms while at an intermediate-high pretest risk for IHD

Exclusion criteria

• Women with known CAD
• Women scoring <5 METs on the DASI
• Nursing or pregnant females
• Nuclear medicine study within the preceding 10 days
• Electrocardiographic abnormalities precluding interpretation of peak stress changes including: Left bundle branch block, electronic ventricular pacemaker, left ventricular hypertrophy, WPW, and resting ST-T wave changes. Additionally, patients currently on digoxin therapy
• Significant valvular heart disease (i.e. severe aortic stenosis or regurgitation, or severe mitral insufficiency)
• Hemodynamic instability (blood pressure >210/110 ml/Hg or <90/60 mm/Hg)
• Left ventricular systolic dysfunction with a left ventricular ejection fraction less than 30 %
• Unavailability for long-term follow-up