Usefulness of Serial Assessment of Natriuretic Peptides in the ...

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Review Paper

Usefulness of Serial Assessment of Natriuretic Peptides in the Emergency Department for Patients With Acute Decompensated Heart Failure

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cute decompensated heart failure (ADHF) is one of the leading causes of adult hospitalization in industrialized countries, particularly in patients older than 65 years, and it is responsible for 4 or 5 annual rehospitalizations in these patients.1–3 The usefulness of measuring brain natriuretic peptide (BNP) and N-terminal prohormone brain natriuretic peptide (NTproBNP) in the diagnosis and the management of congestive heart failure is well known.4,5 Both BNP and NTproBNP levels are useful for diagnosis in patients presenting with undifferentiated dyspnea in the emergency department (ED) and have been shown to accurately reflect heart failure severity and prognosis.5–8 Moreover, in some studies, serial evaluations of BNP have been demonstrated to be useful in clinical management.9 Our group recently reported that repeated determinations of NTproBNP in patients with ADHF in the ED can be useful in the differential diagnosis between acute dyspnea of cardiac origin and dyspnea of other causes. Serial measures can also be useful in decision making for hospital discharge after treatment optimization. In fact, a significant reduction of NTproBNP obtained 7 days after admission parallels clinical improvement in these patients.10 BNP and NTproBNP have different serum half-lives,11 estimated at 20 and 120 minutes, respectively. It is possible that after acute diuretic treatment, these 2 peptides may demonstrate different responses in mirroring natriuretic peptides in the ED

The value of natriuretic peptides, both B-type natriuretic peptide (BNP) and N-terminal prohormone brain natriuretic peptide (NTproBNP), for determining diagnosis, severity, and prognosis of emergency department (ED) patients with acute decompensated heart failure (ADHF) has been well documented. Emerging data support the hypothesis that repeated natriuretic peptide determinations in the acute phase of ADHF may assist in confirming the diagnosis, monitoring drug therapy, and evaluating the adequacy of patient stabilization. Data from the authors’ group demonstrate that in patients admitted to the ED for acute dyspnea, serial NTproBNP measurement at admission and 4, 12, and 24 hours later was useful in confirming the diagnosis of ADHF compared with patients with chronic obstructive pulmonary disease. Moreover, in the same patients receiving intensive intravenous diuretic therapy, there was a progressive reduction of NTproBNP blood levels from hospitalization to discharge (P600 pg/mL. Patients with severe decompensation frequently show levels >1000 pg/mL.9 In our study,10 mean admission NTproBNP plasma levels in ADHF were 5710±9967 pg/ mL and declined to 3671±2647 pg/ mL at discharge. Generally, in patients older than 75 years, as in the population we studied, NTproBNP levels are 4 or 5 times greater than those of BNP.16 The NTproBNP value in our study was much higher than the diagnostic cutpoint of >406 pg/mL july . august 2008 . supplement 1

in the currently accepted literature.9 However, it should be noted that our results come from a population of patients older than 75 years. While our study suggests that BNP provides better prognostic information, the overall literature is unclear as to whether it is better to use serial BNP or NTproBNP in the management of ADHF in the ED, and other publications comparing these hormones do not provide definitive conclusions.17,18 Our data suggest that the repeated ED evaluation of NTproBNP in ADHF patients should be limited to the initial diagnosis and discharge.10 In other words, if the ED physician decides to obtain serial NTproBNP assessments with the aim to confirm the clinical improvement, it seems to be of limited help to repeat the blood determination of this hormone before discharge.10 For patients with delayed presentation or if the NTproBNP levels are obtained at later blood draws, the 4and 12-hour determinations may still be useful as a diagnostic test for ADHF, as it is evident in our study that the blood levels of NTproBNP at these times were in the same range as those obtained at admission.10 While a correct diagnosis is crucial for the ED physician and should be useful in terms of cost-effectiveness by resulting in better patient management and a reduction of the need for repeated future hospitalizations, in the case of NTproBNP it is reasonable to criticize the excessive costs of repeated determinations only for diagnostic confirmation. The strength of BNP for evaluating the adequacy of rapid clinical stabilization in ADHF patients after intravenous diuretic treatment is due to the fact that it has earlier therapeutically induced changes (24–48 hours) than does NTproBNP. Serial BNP measurement has been used by other authors

to optimize cardiovascular drug dosing. This includes both b-blockers18,19 and angiotensin-converting enzyme inhibitors.20–23 Before our study, few data were available to suggest the appropriate use of natriuretic peptide measurement in regards to ED diuretic therapy.23,24 In ADHF, patients with BNP values between 200 and 500 pg/mL are often in NYHA class II or III and require more consistent diuretic therapy.23 For goal-directed BNP-guided therapy, the standard therapies of angiotensin-converting enzyme inhibitors, b-blockers, and diuretics are titrated until a BNP goal of