Triage of Chest Pain Patients

ABSTRACT & COMMENTARY

Synopsis: Use of this critical pathway for chest pain may reduce resource use.

Source: Nichol G, et al. Ann Intern Med 1997;127:996-1005.

Chest pain patients are a common and costly problem to health care systems. Innovative diagnostic approaches have been developed, and algorithms have been devised to determine who can safely be sent home. Critical pathways are popular because they allow for simultaneous management of the patient and feedback to the providers regarding outcomes. Thus, Nichol and associates devised a critical pathway involving emergency department observation and exercise testing for the management of patients with chest pain at low risk for the complications of acute ischemic heart disease. (See Figure.)

The critical pathway was based upon published literature, guidelines and expert opinion. It was then retrospectively applied to 4585 patients older than 30 years with acute chest pain who did not have a history of trauma or an abnormal chest x-ray. Patients were not eligible for the pathway if chest pain was ongoing or associated with heart failure or ECG evidence of myocardial ischemia and infarction, or if they were so low risk that they could be discharged from the emergency room immediately. Of the 2898 patients eligible for the pathway, 93% had a benign course. Application of the pathway would have resulted in 17% fewer admissions and 11% fewer hospital days. Nichol et al conclude that use of this critical pathway for chest pain may reduce resource use.

Figure

Chest pain triage critical pathway

COMMENT BY MICHAEL H. CRAWFORD, MD

Critical pathways have become part of modern hospital jargon. They appear to be management algorithms, but they lack the detail necessary to describe management. Instead, there is plenty of room for physician judgment within the framework of the pathway. Thus, critical pathways do not conflict with guidelines or treatment algorithms. Also, when they are in place in a hospital, they provide the end points necessary to evaluate outcomes and feedback information to the physicians.

The interesting aspect of this pathway is the use of the ability to exercise as the first decision step. Nichol et al reasoned that the patient unable to exercise for whatever reason was at higher risk and required a longer observation period. Of those observed for six hours who remained stable, 1.2% had acute myocardial infarction vs. 0.4% of stable patients after 12 hours. This suggests that the longer observation period may be preferable if the goal is to keep the missed infarction rate below 1%. Also, the six-hour observation period only had one creatine kinase MB measurement, whereas the 12-hour observation protocol called for at least two, two hours apart. The 12-hour observation period agrees with other reports evaluating the accuracy of algorithms using serum markers and may now be the preferred strategy.

A critical feature of the pathway was exercise testing at six hours in those who could exercise. This was largely ECG exercise testing since these patients had relatively normal ECGs. The safety and efficacy of exercise testing at six hours after one negative creatine kinase MB measurement has not been validated but appears to be feasible in this analysis. The lack of any stress testing in the 12-hour group is a bold feature. Many would feel more comfortable with pharmacologic stress tests for many of these patients before discharge. The critical pathway concept doesn’t preclude such testing but was not considered in this analysis. Of those patients deemed ineligible for the pathway because of higher perceived risk, 18% had myocardial infarction. These data support the concept that history, physical examination, and the ECG are fairly accurate at identifying a high-risk group. Of the total patients with chest pain evaluated by their pathway, one-third would be admitted and one-third would be sent home immediately. Unfortunately, this report doesn’t describe the outcome of the latter group. Some of them could have had events and could pose a potential liability risk.

If the Federal guidelines are followed, these patients should have physician follow-up within 72 hours but not necessarily exercise testing. In our practice, we tend to recommend later exercise testing for almost all patients sent immediately home from the emergency room.

Among the third observed in the emergency room, the infarct rate was low but 15% developed unstable angina, and 0.5% developed life-threatening complications. However, of the ineligible group who would have been admitted immediately, 45% were diagnosed as unstable angina and 6% had life threatening complications. Thus, 15% subsequently requiring admission for unstable angina in the emergency room observation group seems reasonable and suggests that the pathway performs well.

Nichol et al conclude that the use of such a critical pathway will reduce resource use, but little cost data or analysis are provided. Avoiding admission could save costs, providing the combined costs of emergency room observation, serum tests, and stress tests do not nullify the savings. Exercise ECG is not expensive, but pharmacologic stress with imaging or other diagnostic approaches could be. Thus, despite the attractiveness of this approach, true cost savings are unknown. (Dr. Crawford is Robert S. Flinn Professor, Chief of Cardiology, University of New Mexico, Albuquerque.)

The use of critical pathways to triage chest pain patients likely will:

a. reduce hospital costs.

b. improve MI survival.

c. improve unstable angina outcomes.

d. prevent litagation.