The survey also questioned the clinical use of the B-type natriuretic peptide (BNP) as a cardiac marker, or if this marker was being used for the differential diagnosis of dyspnea patients and congestive heart failure management only. ACEP’s clinical policy briefly comments on the prognostic, not diagnostic, role of BNP in AMI, stating that elevated BNP has been shown to predict higher rates of morbidity and mortality in patients with acute myocardial infarction. Table 3 demonstrates an overwhelming majority of respondents do not use BNP as a cardiac marker, using it for dyspnea and CHF patients only. Of note, none of the academicians used BNP as a cardiac marker in the emergency department.

Finally, the survey asked whether respondents had bedside cardiac markers available in their institution; if yes, which one; and if not, why not. As demonstrated in Table 4, less than a third of respondents have bedside cardiac marker testing. For those who did not, as shown in Table 5, the most common reason was that lab turnaround time was just as fast. Other comments included expense and lab politics. Of interest, three respondents who answered “no” had cardiac marker bedside testing but abandoned it because of QC problems and expense, because rapid cardiac markers made no difference in clinical decisionmaking, and because of a high false-negative rate.

This study suggests that a combination of troponin and CKMB may be the most popular protocol to rule out AMI in patients in the emergency department. BNP is rarely if ever used as an AMI marker and is primarily used for the differential diagnosis of dyspnea and management of congestive heart failure. Both of these practices are consistent with the ACEP 2006 clinical policy recommendations for cardiac marker use based on clinical presentation. The survey also suggests that bedside cardiac marker testing requires many resources, does not necessarily improve throughput, and may be a potentially expensive and unnecessary alternative for emergency departments that have well functioning hospital laboratory services. Nonetheless, having some cardiac marker strategy as a part of the evaluation of possible AMI is a part of the evaluation of chest pain in all emergency departments surveyed.

References

• Ann. Emerg. Med. 2006;48:270-301.
• Ann. Emerg. Med. 2009;53:321-8.

Dr. Parker is a regional medical director for EmCare Central Region and clinical assistant professor of emergency medicine at Texas Tech University Health Sciences Center, El Paso. Dr. Suter is a past president of the American College of Emergency Physicians and the International Federation for Emergency Medicine.