Objectives: The purpose of this study was to define the value of exercise echocardiography as an independent predictor of cardiac events in women with known or suspected coronary artery disease (CAD), incremental to the data provided by clinical evaluation and exercise testing.
Background: Exercise echocardiography is more accurate than exercise electrocardiography for the identification of CAD in women. However, the prognostic implications of exercise echocardiography, especially relative to exercise electrocardiography, are undefined.
Methods: Symptom-limited exercise echocardiography was performed in 549 consecutive women between 1989 and 1993. Echocardiography and electrocardiography were performed before and after treadmill exercise; an abnormal result on exercise electrocardiography was defined by ST segment depression > 0.1 mV, ischemia by exercise echocardiography as a new or worse wall motion abnormality after exercise and scar by akinesia or dyskinesia at rest. After exclusion of six patients with uninterpretable studies (1%) and 35 (6%) lost to follow-up, 508 women (mean [+/-SD] age 55 +/- 11 years) were followed up for 41 +/- 10 months for cardiac-related death, infarction or late revascularization.
Results: The group attained 92 +/- 10% of age-predicted maximal heart rate, with an exercise capacity of 7 +/- 2 metabolic equivalents. Of 420 women with an interpretable electrocardiogram, significant ST segment changes were present in 68 (16%). Results of exercise echocardiography were normal in 413 (81%) women, positive for ischemia in 66 (13%) and scar only in 29 (6%). No events occurred in 444 patients (89%), and 19 underwent primary revascularization (within 3 months of exercise test). Cardiac events occurred in 36 women (7%), including 17 who died of cardia causes and 19 who had a myocardial infarction or required late revascularization for progressive symptoms. On univariate analysis, the variables associated with cardiac mortality and total cardiac events were a history of CAD, diabetes, left ventricular hypertrophy, exercise capacity and echocardiographic evidence of myocardial ischemia and infarction. A Cox proportional hazards model showed the independent predictors of outcome to be known CAD (odds ratio [OR] 6.6, 95% confidence interval [CI] 3.2 to 13.7, p < 0.00001) and echocardiographic ischemia (OR 4.3, 95% CI 2.1 to 8.7, p < 0.0001). The prognostic value of exercise echocardiography incremental to clinical and exercise variables was demonstrated using sequential Cox models.
Conclusions: In this large cohort of women, exercise echocardiography provided key prognostic information incremental to clinical and exercise testing data.