Impact of myocardial infarction symptom presentation on emergency response and survival

Abstract

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.

Initial symptoms of myocardial infarction – Consequences and methodological approach

“…For both Paper A and C the type of MI was defined as: STEMI (ICD-10: I210B, I211B, I213), NSTEMI (ICD-10: I210A, I211A, I214), Unknown/Other (ICD-10: I210, I211, I219, I219A). 10 As the 1813-medical helpline receive calls for inquests, it is in fact possible that patients were dead at the time of call. To reduce risk of inclusion of patients who had already passed at the time of call, we excluded patients who had registrations of inquest or descriptions indicating that the patients had passed.…”

“…Patients with missing recording of symptom or recordings not informative of the patients condition were excluded. 10 Further information of these calls can be found in Section 9.1. Additionally, patients registered as unconscious or suspected dead at time of call were excluded.…”

“…In addition information of treatment assigned during patient transportation in ambulances were defined using the electronic prehospital patient record. 10,57,74 Recorded symptoms (Paper A and C)…”

“…Both protocol systems are criteria based with a hierarchically ordering of the symptoms, such that symptoms are grouped according to the primary symptom or complaint followed by sub-symptoms. 10,67,74 The assigned criterion is used for registration as well as assigning of appropriate vehicle if needed. 57…”

“…[3][4][5] Often, the first medical contact for MI patients is a telephone consultation with a general practitioner, a health care center, an out-of-hours medical service, or an emergency medical service. [6][7][8][9][10] The ability to correctly recognize the severity of MI patients' symptoms and refer to treatment during the first medical contact is important to reduce treatment delay and possibly mortality, 11,12 but can be challenging in the absence of chest pain. Prehospital misrecognition and long delays might be an important contributing factor to the observed differences in mortality among MI patients with and without chest pain.…”