Electrocardiography in Women

Abstract

In the just over 100 years since the first ECG was performed,1 the ECG has become the most extensively used noninvasive diagnostic and prognostic tool in cardiology. Used both at rest and during provocative exercise, the 12-lead ECG has impressive, if imperfect, utility for rhythm analysis, detection of ischemic and hypertrophic heart disease, and outcome prediction in a variety of clinical settings, with a large body of literature that illustrates and supports these applications. The first observation of gender differences in the ECG was published 85 years ago by Bazett,2 demonstrating that women have significantly longer QT intervals than men despite having higher heart rates. However, despite a growing body of literature demonstrating significant gender differences in QRS amplitudes and duration,3–6 QT intervals,5,7,8 ST-segment deviation,9,10 and novel, computer-based measurements of T-wave complexity,8,11 few ECG criteria routinely use gender-specific diagnostic criteria, and there has been a relative paucity of data on the prognostic performance of ECG variables in women. Articles pp 473 and 481 Two studies in the current issue of Circulation by Rautaharju and colleagues12,13 provide a wealth of new findings and impetus for further study of the ECG in women. Using well-validated computerized ECG methodology, the authors examined the value of a number of ECG variables for predicting incident coronary heart disease and its mortality, incident congestive heart failure, and total mortality in more than 38 000 women participating in the dietary modification trial of the Women’s Health Initiative. Although both studies reconfirm the predictive value of ECG evidence of prior Q-wave myocardial infarction (MI), the principle new findings are the strong predictive value of various ECG measures of repolarization, and in particular of the QRS/T angle,12,13 a measure of the spatial angle between mean QRS and T vectors. In the …