Gender Differences in the Prognostic Value of Exercise Treadmill Test Characteristics
Does the prognostic significance of exercise treadmill testing (ETT) variables differ by gender?
The study population from the clinical registry of Kaiser Permanente of Colorado was used for the present analysis. Members over the age of 18 years who were referred for ETT between July 2001 and June 2004 were included. All ETTs were symptom-limited testing with the majority using a Bruce protocol. Data collected included occurrence of symptoms, ST-segment deviations, exercise capacity (metabolic equivalents [METs]), heart rate recovery defined as decrease in heart rate from peak exercise to 1-minute recovery, and chronotropic incompetence (defined as <80% of patients’ heart rate reserve [220 – age – resting heart rate] at peak exercise). The primary outcomes of interest were all-cause mortality and hospitalization for myocardial infarction (MI) over a mean follow-up of 3.2 years. Multivariate models were adjusted for patient and stress test characteristics, and were stratified by gender to determine the relationship between ETT variables and outcomes.
A total of 9,569 consecutive patients were included, of which 46.8% were women. Overall, exercise capacity and heart rate recovery were significantly associated with all-cause death. Exercise capacity, chest pain, and ST-segment deviations were significantly associated with subsequent MI. In general, the relationship between ETT variables and outcomes was similar between men and women, except for abnormal exercise capacity, which had a significantly stronger association with death in men (hazard ratio [HR], 2.89; 95% confidence interval [CI], 1.89-4.44), but not for women (HR, 0.99; 95% CI, 0.52-1.93). In contrast, chronotropic incompetence had a significantly stronger relationship with MI for women (HR, 2.79; 95% CI, 0.94-8.27) than for men (HR, 1.29; 95% CI, 0.74-2.20).
The authors concluded that several traditional ETT variables had similar prognostic value in both men and women. However, exercise capacity was more prognostically important in men, and chronotropic incompetence was more important in women.
It has long been known that gender differences exist for ETT as a diagnostic tool to detect coronary artery disease; however, as these investigators point out, variables such as chronotropic incompetence which have prognostic importance, have not been well studied in terms of gender differences. Further understanding of such variables will assist in improving diagnostic information for women with heart disease and those who are at risk for MI.
Keywords: Coronary Artery Disease, Myocardial Infarction, Follow-Up Studies, Heart, Colorado, Heart Rate, Exercise Test
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