Any ECG Abnormality Is Suspicious for Postmenopausal Women

CHICAGO, March 8 -- Any abnormal ECG finding was an independent predictor of myocardial infarction, stroke, and coronary heart disease death in asymptomatic postmenopausal women, according to researchers here.

A post hoc analysis of data from more than 14,700 women enrolled in the Women's Health Initiative revealed that minor ECG abnormalities increased the risk of coronary heart disease by 55%, while major ECG abnormalities were associated with a three-fold increase in risk, said Pablo Denes, M.D., of Northwestern.

Women who developed new ECG abnormalities during the study had a hazard ratio of 2.60 (95% CI, 1.08-6.27) for coronary heart disease events and 2.86 (95% CI 1.69-4.83) for cardiovascular disease events, Dr. Denes and colleagues reported in the March 7 issue of the Journal of the American Medical Association.

Moreover, the risk associated with ECG abnormalities was incremental, so that when the ECG data were factored in to Framingham risk scores the area under the receiver operating characteristic curve (ROC) increased form 0.69 to 0.74, he said.

The use of hormonal therapy did not significantly affect the overall cardiovascular disease risk assessment by the ECG, he said.

The Women's Health Initiative randomized 7,593 of 14,749 healthy postmenopausal women to estrogen plus progestin or placebo. All women had ECG studies at baseline and again at three years.

At baseline 9,744 women had ECGs with no evidence of abnormalities, 4,095 had minor ECG abnormalities, and 910 women had evidence of major abnormalities on ECG. After three years, 405 women who had normal ECGs at baseline had developed ECG abnormalities.

In general women who had baseline ECG abnormalities were older, had a higher body mass index, and were more likely to have a history of diabetes, hypercholesterolemia, and hypertension (P

Incident ECG abnormalities included new evidence of atrial fibrillation or flutter, prolonged ventricular excitation, prolonged ventricular repolarization, left ventricular hypertrophy, Q-wave MI, or ischemic ST-T evolution.

The authors said their study was limited by several factors including the homogeneous nature of the population (84% of the women were white). Moreover, not all of the women who had baseline ECGs returned for repeat studies at three years.

Additionally, the Women's Health Initiative was terminated when the data safety monitoring board determined that the estrogen-progestin therapy was associated with increased risk of stroke, deep vein thrombosis, and breast cancer, which limited the follow-up following second ECGs. Finally, the researchers said that data on LDLs as well as Framingham risk score determinations was incomplete.

Nonetheless, the authors concluded that because ECGs are low-cost, widely available, and easily interpreted, they may "be a useful tool for assisting in the prediction of future cardiovascular events in asymptomatic postmenopausal women."