This study assessed patterns in time to presentation among patients with acute myocardial infarction (AMI) and attempted to identify factors associated with delayed arrival. All acute care medical centers in the United States were sampled for an 8-month period (from January 1994 to February 1996) for Medicare beneficiaries hospitalized with a principal discharge diagnosis of AMI. This study included all subjects aged 65 years and older with symptoms consistent with AMI and a confirmed diagnosis of AMI who were admitted from home or from an outpatient clinic. The final sample included 102,339 patients.

The vast majority of the patients were white (90.9%). With regard to timing of presentation, 70.6% of the patients presented within 6 hours of symptom onset, 11.6% presented in 6-12 hours, and 17.8% arrived after 12 hours. Patients arriving after 6 hours (versus those arriving within 6 hours) were older and more likely to be women and nonwhite. This group also had a greater prevalence of diabetes and prior angina, but they were less likely to have prior myocardial infarction, PTCA, or CABG or to present with shock or arrest. Additionally, they were more likely to reside in impoverished areas, to present to an outpatient clinic for initial evaluation, and to arrive during daytime hours. Process of care issues were also associated with time to presentation, as patients presenting during off hours were less likely to have substantial delays. Regression analyses largely confirmed the findings that these variables were independent predictors of late presentation. With regard to race, SES (zip-code level poverty), and gender, there were significant interactions. Although 3-way interactions were not statistically significant, all combinations had significantly higher odds of a delay greater than 6 hours compared with white, non-poor, males.

The authors conclude that a large proportion of patients (more than 25%) presented more than six hours after symptom onset and factors predictive of delayed presentation include not only clinical characteristics, but also sex, race, SES, and process of care issues. "The present analysis reinforces the need to reduce the time to presentation among elderly patients with AMI. Our findings suggest that target groups should include women, minorities, and the poor, as well as patients with diabetes mellitus or chronic angina."

With regard to racial differences, "physician and patient perception may be contributing. Past studies indicate that black-white disparities in coronary care relate both to physician practice patterns, which may include differential patient counseling across races, and to patient trust and understanding of health care. These studies indicated that black patients face several other logistical barriers to treatment as well. It is likely that each of these factors contributed to the association of race and SES with delayed arrival."