Impact of myocardial infarction symptom presentation on emergency response and survival

Aims: We examined associations between symptom presentation and chance of receiving an emergency dispatch and 30-day mortality among patients with acute myocardial infarction (MI).

Methods and results: Copenhagen, Denmark has a 24-h non-emergency medical helpline and an emergency number 1-1-2 (equivalent to 9-1-1). Both services register symptoms/purpose of calls. Among patients with MI as either hospital diagnosis or cause of death within 72 h after a call, the primary symptom was categorized as chest pain, atypical symptoms (breathing problems, unclear problem, central nervous system symptoms, abdominal/back/urinary, other cardiac symptoms, and other atypical symptoms), unconsciousness, non-informative symptoms, and no recorded symptoms. We identified 4880 emergency and 3456 non-emergency calls from patients with MI. The most common symptom was chest pain (N = 5219) followed by breathing problems (N = 556). Among patients with chest pain, 95% (3337/3508) of emergency calls and 76% (1306/1711) of non-emergency calls received emergency dispatch. Mortality was 5% (163/3508) and 3% (49/1711) for emergency/non-emergency calls, respectively. For atypical symptoms 62% (554/900) and 17% (137/813) of emergency/non-emergency calls received emergency dispatch and mortality was 23% (206/900) and 15% (125/813). Among unconscious, patients 99%/100% received emergency dispatch and mortality was 71%/75% for emergency/non-emergency calls. Standardized 30-day mortality was 4.3% for chest pain and 15.6% for atypical symptoms, and associations between symptoms and emergency dispatch remained in subgroups of age and sex.

Conclusion: Myocardial infarction patients presenting with atypical symptoms when calling for help have a reduced chance of receiving an emergency dispatch and increased 30-day mortality compared to MI patients with chest pain.