The relationship between chest pain duration and the incidence of acute myocardial infarction among patients with acute chest pain.

Objective: Eight to ten million individuals are evaluated for chest pain (CP) in Emergency Departments (ED) in the United States each year. CP characteristics are an important factor used to help determine a diagnosis. We studied the relationship between the duration of CP and the diagnosis of acute myocardial infarction (AMI) in patients evaluated in the ED.
Methods: The study population consisted of a sub-group analysis of a previously published study. The survey population consisted of 1024 consecutive encounters of patients who were evaluated for possible ACS in the ED of Henry Ford Hospital between January and May of 1999, CP duration could be obtained in 426 who were included in this analysis.
Results: Of the 426 patients included in the study, 38 (8.9%) had a final diagnosis of AMI, with a median CP duration of 120 minutes (interquartile range, 30-240 minutes), compared with 40 minutes (interquartile range, 6-180 minutes) in patients without AMI (p =0.003). In patients with CP duration less than 5 minutes, there were no AMIs and no deaths at 30 days. There were 10 patients dead at 30 days, with a median CP duration of 180 minutes (interquartile range, 120-1440 minutes) compared to 40 minutes (interquartile range, 10-180 minutes) in patients alive at 30 days (p = 0.011). A longer CP duration and ST depression of 1 mm of less were independently associated with a final diagnosis of AMI.
Conclusion: Patients with AMI have longer duration of CP than those without AMI; patients with CP of short duration, less than 5 minutes, are unlikely to have AMI and have a good prognosis at 30 days.