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Left ventricular dysfunction can occur as a part of coronary heart disease, arterial hypertension, valvular disease, and primary myocardial disease. If the left ventricular dysfunction remains untreated and is progressive, the potential for mortality is high, e.g. due to sudden cardiac death.
Chronic cardiac insufficiency is a clinical syndrome caused by impairment of the cardiac pumping function. Based on the symptoms, the severity of cardiac insufficiency is classified in stages (New York Heart Association classification [NYHA] I-IV). Clinical information and imaging procedures are used to diagnose left ventricular dysfunction.3
The significance of natriuretic peptides in the control of cardiovascular system function has been demonstrated. Studies reveal that natriuretic peptides can be used for diagnostic clinical problems associated with left ventricular dysfunction. The following natriuretic peptides have been described: atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), and C-type natriuretic peptide (CNP).
ProBNP is secreted mainly by the ventricle and, in this process, is cleaved into physiologically active BNP and the N-terminal fragment NT-proBNP.
Studies indicate that NT-proBNP can be used in diagnostic and prognostic applications. The concentration of NT-proBNP in serum or plasma correlates with the prognosis of the left ventricular dysfunction.
Fisher, et al. found that congestive heart failure patients with NT-proBNP values above median had a one year mortality rate of 53% compared to 11% in patients below median.
In the GUSTO IV study which involved more than 6800 patients it was shown that NT-proBNP was the strongest independent predictor of one year mortality in patients with acute coronary syndrome.
Three studies involving patients with stable coronary artery disease have shown that elevated levels of
NT-proBNP lead to a greater risk of future adverse events. In these studies, NT-proBNP levels above
450 pg/mL conferred approximately a two- to six-fold increase in risk for cardiac morbidity and/or mortality.
Furthermore, each of these studies demonstrated that the amount of risk increases somewhat as the NT-proBNP levels approach the above value. Therefore, when a patient with stable coronary artery disease has a NT-proBNP level above 450 pg/mL, and is not shown to have congestive heart failure upon further evaluation, the physician should be aware that the elevated NT-proBNP value may have independent prognostic significance. These patients should receive continuing clinical attention according to established guidelines. NT-proBNP values should be assessed in conjunction with other cardiovascular risk factors and clinical findings.
The test is also useful in assigning symptoms to cardiac or non-cardiac causes, and helps to identify subjects with left ventricular dysfunction. The European Society of Cardiology Task Force for the Diagnosis and Treatment of Chronic Heart Failure recommend in their guidelines that natriuretic peptides including NT-proBNP “may be most useful clinically as a rule out test due to consistent and very high negative predictive values”.
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