The effect of estrogen compared to estrogen plus progesterone on the exercise electrocardiogram.
OBJECTIVE
The objective of this study was to evaluate the effect of estrogen compared to estrogen plus progesterone on the stress electrocardiogram (ECG) in relationship to stress-gated myocardial perfusion imaging (MPI) in postmenopausal women.


BACKGROUND
It is generally recognized that estrogen may cause false positive ST depressions on the stress ECG. The effects of estrogen plus progesterone are not known. This study was performed to define the effects of these agents on the stress ECG correlated with results from MPI.


METHODS
We evaluated 140 postmenopausal women-31 not taking any hormone replacement therapy (HRT); 75 taking estrogen alone; and 34 taking estrogen plus progesterone. Women with a history of coronary artery disease (CAD), cardiomyopathy, or an abnormal resting ECG were excluded. All women underwent a symptom-limited treadmill test and MPI.


RESULTS
The overall sensitivity and specificity of the stress ECG compared to MPI in women not taking HRT was 54% and 78%, respectively. In women taking estrogen or estrogen plus progesterone, the sensitivity was unchanged. The power to detect clinically meaningful sensitivity difference (10%) was poor (p = 0.09). The specificity was reduced to 46% (p < 0.01) in women on estrogen therapy. In women taking estrogen plus progesterone, specificity was 80%.


CONCLUSIONS
Our results suggest that estrogen increases the false positive rate of the stress ECG. This decreased specificity is countered by co-administration of progesterone. Nonetheless, because the sensitivity of the stress ECG is only 50% to 57% in postmenopausal women, women at risk should have imaging in conjunction with stress for the optimal detection of CAD.
D000368:Aged; D003324:Coronary Artery Disease / Q000175:diagnosis*; D003326:Coronary Circulation / Q000187:drug effects*; D004359:Drug Therapy, Combination; D004562:Electrocardiography / Q000187:drug effects*; D015914:Estrogen Replacement Therapy; D004966:Estrogens, Conjugated (USP) / Q000008:administration & dosage / Q000494:pharmacology*; D005080:Exercise Test / Q000187:drug effects*; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008525:Medroxyprogesterone / Q000008:administration & dosage / Q000494:pharmacology*; D008875:Middle Aged; D045167:Progesterone Congeners / Q000008:administration & dosage / Q000494:pharmacology*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
D004966:Estrogens, Conjugated (USP); D045167:Progesterone Congeners; D008525:Medroxyprogesterone