Myocardial infarction: Sex differences in symptoms reported to emergency dispatch

Background. Emergency management of myocardial infarction (MI) is time-critical, because improved patient outcomes are associated with reduced time from symptom onset to definitive care. Previous studies have identified that women are less likely to present with chest pain. Objective. We sought to measure the effect of sex on symptoms reported to the ambulance dispatch and ambulance times for MI patients. Methods. The Western Australia Emergency Department Information System (EDIS) was used to identify patients with emergency department (ED) diagnoses of MI (ST-segment elevation MI and non-ST-segment elevation MI) who arrived by ambulance between January 1, 2008, and October 31, 2009. Their emergency telephone calls to the ambulance service were transcribed to identify presenting symptoms. Ambulance data were used to examine ambulance times. Sex differences were analyzed using descriptive and age-adjusted regression analysis. Results. Of 3,329 MI patients who presented to Perth EDs, 2,100 (63.1%) arrived by ambulance. After predefined exclusions, 1,681 emergency calls were analyzed. The women (n = 621; 36.9%) were older than the men (p < 0.001) and, even after age adjustment, were less likely to report chest pain (odds ratio [OR] = 0.70; 95% confidence interval [CI] 0.57, 0.88). After age adjustment, ambulance times did not differ between the male and female patients with chest pain. The women with chest pain were less likely than the men with chest pain to be allocated a "priority 1" (lights and sirens) ambulance response (men 98.3% vs. women 95.5%; OR = 0.39; 95% CI 0.18, 0.87). Conclusion. Ambulance dispatch officers (and paramedics) need to be aware of potential sex differences in MI presentation in order to ensure appropriate ambulance response.