Postmenopausal heart disease may not show up on ECG

A normal electrocardiogram (ECG) doesn’t necessarily rule out coronary heart disease (CHD) in postmenopausal women, a new study shows.

Researchers from the Emory University School of Medicine in Atlanta reviewed the ECGs of 10,101 women 55 years and older who participated in the Raloxifene Use for the Heart (RUTH) trial. Of the 59% of ECGs that were normal, 50% were from women with documented CHD and 69% were from women at risk of CHD. Forty-three percent of women with CHD who reported a previous myocardial infarction (MI) had a normal ECG. The study was published in the American Journal of Cardiology (2010;106:1580-1587).

“There were high percentages of normal electrocardiograms in the increased-risk and documented CHD groups of RUTH participants, with substantial discrepancy between MI history and ECG MI documentation,” the authors write.

They note that “the ECG findings substantially underestimated presence of MI, although an ECG Q-wave MI likely indicated an undiagnosed coronary event in women at increased risk of CHD, particularly in women who smoke and in those with angina.” Eleven percent of women in the risk group for CHD who hadn’t reported a previous MI showed ECG evidence of a silent Q-wave MI.

The percent of abnormal ECGs rose with increasing age-the factor most often associated with abnormal findings-and was significantly higher in women with diabetes. Angina and coronary artery bypass graft surgery, but not percutaneous coronary intervention, also were associated with ECG abnormalities.