NT-proBNP A new test for Diagnosis, Prognosis and Management of Congestive Heart Failure
Rahul Sakhuja Cardiology Division and Department of Medicine, Massachusetts General Hospital, Harvard Medical School , James L Januzzi Cardiology Division and Department of Medicine, Massachusetts General Hospital, Harvard Medical School
Management of CHF
NT-proBNP is clearly useful for diagnosis and prognosis of CHF, and may be useful for monitoring and guiding therapy to improve such potential risk. Bettencourt and colleagues observed in 176 hospitalized patients that plasma NT-proBNP levels decreased significantly in patients whose New York Heart Association (NYHA) classification improved.(14) Moreover, aggressive employment of therapies of proven value in CHF such as ACE inhibitors or betablockers decreased NT-proBNP levels, paralleled by improved outcomes including fewer total cardiovascular events, and delayed times to first event (see Figure 3).(27)
Figure 3: Outcomes of Patients Treated with NT-proBNP Guided Therapy Versus
Standard Clinical Judgment. NT-proBNP guided therapy was associated with fewer clinical events
Reproduced with permission from Troughton et al.28
In addition to guiding therapy with agents such as ACEinhibitors, NT-proBNP may be of particular use in the guidance of CHF therapy with nesiritide, a synthetic BNP analogue with vasodilator and natriuretic effects. As nesiritide is 100% homologous to endogenous BNP, use of this agent understandably alters assayed levels of BNP rendering biomarker-guided therapy with BNP useless. However, NT-proBNP measurement is not affected by nesiritide. Therefore, in the settings of nesiritide therapy, NT-proBNP proves more useful in monitoring therapy and managing heart failure.
Other Uses of NT- proBNP
While much of the literature has focused on the natriuretic peptides in CHF, it is necessary to point out that NT-proBNP may be elevated in states other than CHF, such as acute coronary syndromes (ACS) as well as pulmonary thromboembolism (PE).
Similar to CHF, ACS patients constitute a large, highrisk population, for which an early diagnostic and prognostic marker would prove useful. Multiple studies of patients with ACS now demonstrate that NTproBNP levels are the most powerful predictor of mortality at presentation (see Figure 4), superior to troponins for this purpose.(28,29) Interestingly, a follow-up study demonstrated that NT-proBNP also identified those most likely to benefit from early invasive strategies for the management of their ACS.(30)
In addition to CHF and ACS, elevations of NT-proBNP may be powerfully prognostic among patients with acute PE. In 73 patients with acute PE, elevated NT-proBNP levels predicted in-hospital complications (including death) compared with patients with low NT-proBNP levels. In this study, the negative predictive value of NTproBNP was 97%, similar to that of d-dimer.(31)
Conclusion
Aggregate data now point to the exceptional value of NT-proBNP for the diagnosis, prognosis, and management of patients with acute CHF.While many studies suggest that NT-proBNP and BNP are similar in their potential as a marker for heart failure, some recent studies conclude that NT-proBNP is a more discerning marker in many common clinical scenarios, such as diastolic CHF. In addition, the value of NT-proBNP for diagnosis and prognosis extends to other cardiovascular disease states such as ACS and PE. This versatile marker should help to optimize the care of a wide range of patients with prevalent cardiovascular illnesses.
