Am Fam Physician. 2004 Nov 1;70(9):1796-1797.
Because heart failure is the most common reason for hospitalization of persons older than 65 years, efficient management of these patients is important. Even with a careful history, physical examination, and chest radiograph, it often is difficult to decide whether heart failure is present in a patient with acute dyspnea. B-type natriuretic peptide (BNP) has demonstrated sensitivity and specificity in the diagnosis of heart failure. This peptide is released by ventricular myocytes when heart failure causes increased wall stretch. Mueller and colleagues investigated the use of BNP in the evaluation of patients with dyspnea.
The study was performed at an academic hospital center with 665 consecutive patients presenting to the emergency department with acute dyspnea. Exclusion criteria included any traumatic cause for dyspnea, renal failure, and cardiogenic shock. A total of 452 patients was enrolled in the trial and randomized to standard clinical evaluation or this same evaluation with the inclusion of a rapid assay for BNP.
The authors used a BNP level of 100 pg per mL as a cutoff indicating where heart failure was deemed unlikely, and an elevation higher than 500 pg per mL as an indication that heart failure was the most likely cause of dyspnea. With intermediate values, physicians relied on other standard evaluation measures to decide whether heart failure was present.
The study was designed to determine the extent to which the additional clinical information provided by the BNP assay influenced hospital length of stay or total cost of treatment. The mean age of study participants was 71 years, and about 40 percent were women. Patients typically had multiple chronic medical conditions. The most common comorbidities were coronary artery disease, hypertension, chronic obstructive pulmonary disease, and diabetes.
Use of the BNP assay decreased the average time spent in the emergency department before initiation of appropriate therapy from 90 to 63 minutes. More rapid determination of the cause of dyspnea and institution of treatment with use of the BNP assay translated into a decreased need for hospitalization (this rate dropped from 85 to 75 percent) and admission to an intensive care unit (this rate decreased from 24 to 15 percent). Hospital length of stay was reduced from 11 days with standard evaluation to eight days when BNP results were available, and total cost of care decreased from $7,264 to $5,410.
The authors conclude that inclusion of a rapid assay for BNP in the emergency department evaluation of patients with acute dyspnea decreased the time to initiation of appropriate therapy, subsequent hospitalization rates, length of stay, and overall cost of treatment.
Mueller C, et al. Use of B-type natriuretic peptide in the evaluation and management of acute dyspnea. N Engl J Med. February 12, 2004;350:647–54.
editor’s note: This study adds to the accumulating body of evidence suggesting that BNP assays are going to have a role in the evaluation of acute dyspnea similar to the role of cardiac troponins and other enzyme markers in the work-up of patients with chest pain. While these assays cannot replace clinical judgment, they do provide useful, objective information that may be helpful when standard evaluation measures do not clearly indicate the diagnosis.—b.z.
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