Chest Pain Units

ABSTRACT & COMMENTARY

Source: Farkouh ME, et al. A clinical trial of a chest-pain observation unit for patients with unstable angina. N Engl J Med 1998;339:1882-1888.

Farkouh and associates performed a prospective, randomized trial of a chest pain unit (CPU) compared to the traditional hospital admission (ADM) for "rule-out" myocardial infarction (R/O MI) in patients with unstable angina (USA). Over a sixteen-month period, adult chest pain patients were initially evaluated with a history, examination, and ECG. Based on the results, the eligible patients (determined to be at intermediate risk for short-term cardiac events according to the Agency for Health Care Policy and Research [AHCPR] guidelines) were then randomized to either CPU (212 patients) or ADM (212 patients) group. Exclusion criteria included anatomically-distributed ST segment abnormalities (elevation or depression), obvious noncardiac etiology, co-existing issue requiring hospitalization, and AHCPR low- or high-risk status for cardiac events. CPU patients then underwent serial serum markers and ECG determinations over a minimum of six hours; aspirin (all non-allergic patients) and heparin (selected cases) were administered. If investigations were negative and the course uncomplicated, patients then underwent further evaluation with exercise stress test, nuclear stress test, or stress echocardiography (interpreted by a cardiologist). If positive, the patient was admitted to a cardiologist; if negative, the patient was discharged, with cardiology follow-up within 72 hours. The six-month end points were cardiac event (primary) and the need for coronary revascularization, additional cardiac investigation, or admission for cardiac reasons (secondary).

An initial 2517 patients were initially evaluated for this study; 424 (17%) patients were enrolled. The rate of primary cardiac event was not significantly different between the two groups: 15 events for ADM patients (13 AMI, 2 CHF) and seven events for CPU group (5 AMI, 1 CHF, 1 death). Among CPU patients with a negative evaluation, no cardiac events occurred after emergency department (ED) discharge; these events occurred in the 114 patients admitted from the CPU due to a positive evaluation. For a six-month period after discharge, cardiac investigations and therapies were greater among patients in the ADM group. Admissions to the hospital were reduced by 45.8% during the study. Farkouh et al concluded that a CPU-based evaluation for patients with USA at intermediate risk for acute cardiac complications is safe, effective, and cost-efficient.

Comment by William J. Brady, MD

This investigation is important in that hospital admission for R/O MI is a costly, frequently used, and commonly unrewarding strategy. With the mandate for a more efficient yet safe method for evaluating such patients, the CPU may offer a reasonable alternative. It is estimated that approximately 20% of hospital EDs in the United States use this approach. Such widespread application of a strategy that lacks a solid scientific justification is alarming though common in the medical world; this report is an initial effort aimed at establishing this scientific support. EDs should not use this information as the sole support to initiate such a strategy.

Other issues to consider prior to developing such a unit include patient entry criteria; the resources, abilities, and desires of the ED; the availability of cardiac diagnostic testing; support from the local cardiology groups; and the effect on the primary care physician. The appropriate patient—not yet conclusively identified in the literature—must be chosen for such an evaluation; this study appropriately excluded patients with ST segment change yet included the difficult-to-evaluate patient with LBBB on the ECG. The ED must have a dedicated area for aggressive cardiac monitoring with dedicated nursing staff and resources, timely return of serum markers, and knowledgeable, motivated physicians. Support from the cardiologist is vital in the form of availability of cardiac diagnostic testing seven days a week, as well as timely outpatient follow-up. Many hospitals can only provide diagnostic testing on a limited basis; without such "risk stratification" prior to discharge from the ED, the patient and physicians are placed at risk. The primary care physician must also be considered in this process, not only in terms of financial issues but also in terms of referral and resource use concerns.