Chest pain in an out-of-hospital emergency setting: no relationship between pain severity and diagnosis of acute myocardial infarction.

Background: Chest pain frequently prompts emergency medical services (EMS) call-outs. Early management of acute coronary syndrome (ACS) cases is crucial, but there is still controversy over the relevance of pain severity as a diagnostic criterion.

Study Objective: The aim of this study was to determine whether there is a relationship between the severity of chest pain at the time of out-of-hospital emergency care and diagnosis of acute myocardial infarction (AMI).

Methods: This was a subsidiary analysis of prehospital data collated prospectively by EMS in a large suburb. It concerned patients with chest pain taken to hospital by a mobile intensive care unit. Pain was rated on EMS arrival using a visual analog, numeric or verbal rating scale and classified on severe or not severe according to the pain score. A diagnosis of AMI was confirmed or ruled out on the basis of 2 plasma troponin measurements and/or coronary angiography results.

Results: Among the cohort of 2,279 patients included, 234 were suitable for analysis, of which 109 (47%) were diagnosed with AMI. The rate of severe pain on EMS arrival was not significantly different between AMI patients and no myocardial infarction patients (49% [95% CI 40 to 58] and 43% [34 to 52], respectively; P = 0.3; odds ratio 1.3 [0.8 - 2.3] after adjustment for age and gender).

Conclusion: In our out-of-hospital emergency setting, the severity of chest pain was not a useful diagnostic criterion for AMI.