Objective: To determine the relationship of age and the percentage of patients presenting to the emergency department with myocardial infarction who meet conventional electrocardiographic and time-to-presentation criteria for thrombolytic therapy.
Design: Prospective cohort study.
Setting: Emergency departments of three university hospitals and four community hospitals.
Patients: Patients enrolled in the Multicenter Chest Pain Study, an investigation of patients aged 30 years or older presenting to the emergency department with the chief complaint of anterior, precordial, or left lateral chest pain unexplained by obvious local trauma or abnormalities on the chest radiograph.
Interventions: None.
Measurements: The frequency of patients who presented with conventional electrocardiographic and time-to-presentation criteria for thrombolysis.
Main results: Of a total of 12,140 patients who were enrolled in the Multicenter Chest Pain Study, 10,850 had information about their electrocardiogram and their time-to-presentation. Acute myocardial infarction occurred in 1,584 patients, 746 of whom were over age 65. Among patients presenting to the emergency department with acute myocardial infarction, the proportion who arrived within 6 hours of the onset of pain and had ST-segment elevation or pathologic Q-waves not known to be old decreased significantly with increasing age, from 34% in patients under 65 years to 18% for those 75 years and older. In addition, comorbidities that would have contraindicated thrombolytic therapy were present in an additional 12% of myocardial infarction patients who were older than 65 years.
Conclusion: Although other analyses have shown that thrombolytic therapy is cost-effective for eligible elderly patients with acute myocardial infarction, only a small percentage of very elderly patients who present to the emergency department with acute myocardial infarctions meet current eligibility criteria to receive it, so thrombolysis is unlikely to narrow the difference in mortality rates for young as compared with elderly patients with acute infarctions.