ECG parameters may predict future CV events in women

Findings could raise awareness of the significance of small vessel disease in women.

Issue: October 2005

Electrocardiographic parameters may help predict the risk of future cardiovascular events among women with suspected myocardial ischemia.

A study published in the Journal of the American College of Cardiology found that several 12-lead ECG parameters, such as the QRS-T angle and the QRS and QTrr duration, were predictive even among relatively healthy women. Researchers suggested that these parameters could be incorporated into a global risk factor score for women.

The ECG research looked at data from the Women’s Ischemia Syndrome Evaluation (WISE), chaired by C. Noel Bairey Merz, MD, director of the Preventive and Rehabilitative Cardiac Center at Cedars-Sinai Medical Center and editorial board member of Cardiology Today’s Preventive Cardiology section.

C. Noel Bairey Merz, MD [photo]
C. Noel Bairey Merz

“We have a standard set of ECG predictors that are time tested and were mostly developed in data sets looking at men. This is now a sex-specific study. Whenever we look at gender differences, we frequently do find differences, and we have to then acknowledge that our standard set should be adjusted,” Bairey Merz said.

Predictive parameters

Data from the WISE trial included 12-lead ECG and quantitative angiographic data from 143 women. The mean age of the women was 59 years. Their mean left ventricular ejection fraction was 64%. All had been referred for clinically indicated cardiac catheterization to evaluate for suspected myocardial ischemia. Thirteen percent had had events during a mean follow-up of more than three years. Several ECG parameters were found predictive of cardiovascular events among these women: a wider QRS-T angle, a wider QRS complex, and a longer QTrr. These parameters in women were statistically significant independent predictors of death, CHF and nonfatal MI.

Patients were 50% more likely to experience mortality for each 10-degree increase in the QRS-T angle (P=.0005). Increased mortality was 75% per 10-ms widening of the QRS complex (P=.004). Longer QTrr was associated with a 46% increase in mortality per 10-ms increase in duration (P=.0004).

“The novelty of this study lies in the fact that abnormalities of these ECG parameters were predictive of events in a relatively healthy population of women even when their values were within the accepted normal range,” researchers reported. Bairey Merz said that the ECG predictors “are helping us to answer the question of minimal disease. These data would suggest that women with minimal disease and open arteries can still be at risk,” she said.

Bairey Merz said one of the motivating factors for observing ECG readings in WISE was the possibility that these readings may be predictive of small vessel disease.

“In the original WISE, we found that small vessel disease is particularly important in women. Small vessel disease has been discounted because it’s not particularly important in men,” she said.

However, researchers on the ARIC (Atherosclerosis Risk in Communities) study noted that ECG parameters were predictive of small vessel disease in women, a finding that has now been confirmed in WISE.

“We are doing further investigation into small vessel disease because it really is predominantly a woman’s problem and has not been acknowledged for the serious problem it is. We need to work to find treatments,” Bairey Merz said. – by Jeremy Moore

For more information:

Triola B, Olson MB, Reis SE, et al. Electrocardiographic predictors of cardiovascular outcome in women: The National Heart, Lung, and Blood Institute-Sponsored Women’s Ischemia Syndrome Evaluation (WISE) Study. J Am Coll Cardiol. 2005;46:51-6.