ECG changes during myocardial ischemia. Differences between men and women.

Women have a higher short-term mortality in acute myocardial infarction (MI) compared with men. This may be partly explained by differences in risk factors such as age and diabetes. However, several reports have focused on the occurrence of a sex bias making women less likely to be subjected to angiography and revascularization as well as aggressive pharmacologic treatment of acute MI. The decision to initiate these procedures is often based on ischemic changes of the electrocardiogram. It was therefore investigated whether differences between men and women in magnitude of electrocardiographic changes during myocardial ischemia could explain some of the differences previously reported. A total of 178 patients with chest pain suggestive of MI (135 men and 43 women) included in a study of thrombolytics were monitored for 24 hours with continuous vectorcardiography. Also, 81 patients with stable angina pectoris undergoing elective angioplasty were monitored during the procedure. In patients admitted with suspicion of MI, the initial summated ST deviation was 178 +/- 146 microV for men as compared with 105 +/- 91 microV for women (P = .002). During angioplasty, men had significantly more pronounced maximum ST deviation during inflation of the balloon (235 +/- 165 vs 156 +/- 89 microV; P = .036). In conclusion, men have more pronounced ST changes than women during myocardial ischemia. When fixed magnitudes of ST deviation are required for initiating therapy such as thrombolytics, this will favor treatment of men. A sex-adjusted limit for administrating thrombolytic drugs may be warranted in the light of the above findings.