Study objective: To evaluate the applicability of a short-stay protocol for exclusion of acute ischemic heart disease without hospital admission and to analyze these results in the context of a conceptual model.
Methods: An observational study of patients who presented with chest pain to the emergency department of an 886-bed inner-city municipal hospital and who needed hospital admission to rule out acute myocardial infarction (AMI). Patients were assessed by ED attending physicians to determine eligibility for an alternative, 12-hour protocol in an ED chest pain observation unit (CPOU) followed by immediate exercise testing. Outcome measures were proportion of patients eligible for the short-stay protocol, risk factor profile, and reasons for exclusion.
Results: Of 500 patients screened, 446 had sufficient data points to determine protocol eligibility. Of these, 238 (53.3%; 95% confidence interval [CI], 48.7% to 57.9%) were found to have low probability for AMI. After study exclusion criteria were applied to the patient cohort, 63 patients (14.1%; 95% CI, 10.9% to 17.3%) were eligible for the protocol. The most common reasons for exclusion were history of coronary artery disease (46%) and inability to perform an interpretable exercise tolerance test (42%).
Conclusion: Although most admitted patients with chest pain (53%) were at low probability for AMI, only a minority (14%) were eligible for a short-stay protocol that required patients to be free of known coronary artery disease and able to perform an exercise tolerance test. Factors affecting the operations and efficiency of a CPOU include clinical characteristics of the target patient population, protocol tests used, and hospital occupancy and reimbursement patterns.