The emerging roles of BNP and accelerated cardiac protocols in emergency laboratory medicine.

BACKGROUND

The role of the clinical laboratory in emergency cardiac medicine is rapidly evolving; with recent redefinitions of acute myocardial infarction (AMI) and unstable angina (UA) based on troponin levels, recommended acceleration of cardiac testing protocols, and increased clinical measurement of B-type natriuretic peptide (BNP). We briefly review the background pathophysiology of acute coronary syndromes (ACS) and congestive heart failure (CHF), along with an overview of the biochemistry and physiology of the natriuretic peptides.

METHODS

The assay principles and performance characteristics of the rapid BNP assays are discussed. The performance characteristics of troponin assays are at the center of controversy regarding the redefinition of AMI and UA, and will be discussed.

RESULTS

We review the rapidly expanding evidence regarding the clinical utility of BNP for CHF patients. While BNP has gained wide acceptance as a rapid diagnostic tool, considerable controversy remains concerning its potential for prognosis, screening, and therapeutic monitoring. Although a thorough discussion of the use of cardiac markers is well beyond the scope of this review, overviews of the redefinitions of AMI and UA, and the trend toward accelerated testing protocols to obtain a quicker diagnosis or ruling-out of AMI are included. In addition to accelerating the retesting of existing markers, a recent test for ischemia modified albumin (IMA) promises another quantum leap in cardiac diagnoses.

CONCLUSIONS

The positive impact of these developments on the healthcare costs and overall improvement in the quality of healthcare delivery will be discussed. A brief analysis of the downstream costs of BNP testing is also offered.