Analysis of sex differences in preadmission management of ST-segment elevation (STEMI) myocardial infarction

Many reports suggest gender disparity in cardiac care as a contributor to the increased mortality among women with heart disease.

We sought to identify gender differences in the management of Myocardial Infarction (MI) Alert-activated ST-segment elevation myocardial infarction (STEMI) patients that may have resulted from prehospital initiation.

A retrospective database was created for MI Alert STEMI patients who presented to the emergency department (ED) of an academic community hospital with 74,000 annual visits from April 2000 through December 2008. Included were patients meeting criteria for an MI Alert (an institutional clinical practice guideline designed to expedite cardiac catheterization for STEMI patients). Data points (before and after initiation of a prehospital alert protocol) were compared and used as markers of therapy: time to ECG, receiving β-blockers, and time to the catheterization laboratory (cath lab). Differences in categorical variables by patient sex were assessed using the χ(2) test. Medians were estimated as the measure of central tendency. Quantile regression models were used to assess differences in median times between subgroups.

A total of 1231 MI Alert charts were identified and analyzed. The majority of the study population were male (70%), arrived at the ED via ambulance (60.1%), and were taking a β-blocker (67.8%) or aspirin (91.6%) at the time of the ED admission. Female patients were more likely than male patients to arrive at the ED via ambulance (65.9% vs 57.6%, respectively; P = 0.014). The median age of female patients was 68 years, whereas male patients were significantly younger (median age, 59 years; P < 0.001). The proportion of patients currently taking a β-blocker or low-dose aspirin did not vary by gender. Overall, 78.2% of the MI Alert patients arriving at the ED were MI2 (alert initiated by ED physician), and this did not vary by gender (P = 0.33). A total of 1064 MI Alert patients went to the cath lab: 766 male patients (88.9%) and 298 female patients (80.8%). Overall, the median time to cath lab arrival was 79 minutes for men and 81 minutes for women (P = 0.38). Overall, the median time to cath lab arrival significantly decreased from MI1 to MI3, (P(trend) < 0.001). For prehospital-initiated alerts (MI3), the median time to cath lab arrival was the same for men and women (64 minutes; P = 1.0). For hospital-initiated alerts, time to cath lab arrival was 82 minutes for male patients and 84 minutes for female patients (P = 0.38). Prehospital activation of the process decreased the time to the cath lab by 19 minutes (P < 0.001; 95% CI, 13.2-24.8).

No significant gender differences were apparent in the STEMI patients analyzed, whether the MI Alert was initiated in the ED or prehospital initiated. Initiating prehospital-based alerts significantly decreased the time to the cath lab.