Usefulness of Serial B-Type Natriuretic Peptide Assessment in Asymptomatic Aortic Stenosis
What are the echocardiographic determinants of change in serum B-type natriuretic peptide (BNP) level during follow-up among asymptomatic patients with aortic stenosis (AS)?
A cohort of 61 asymptomatic patients was studied; patients had at least moderate AS and preserved left ventricular ejection fraction (LVEF), and underwent rest and exercise Doppler echocardiography with concomitant BNP level measurement at baseline. After initial testing, BNP measurement was repeated every 6 months.
Patients were divided into two groups according to the median of BNP changes during follow-up. Using nonexercise echo/Doppler parameters, patients with greater change in follow-up BNP had significantly higher E/e’ ratio; statistically significant correlations were found between BNP changes and E/e’ ratio, and indexed left atrial area. Using exercise echo/Doppler parameters, patients with greater change in follow-up BNP had significantly lower exercise-induced increase in LVEF, with a statistically significant correlation between BNP change and exercise-induced change in LVEF. After adjustment for age, mean aortic pressure gradient, and BNP level at baseline, multivariable analysis identified indexed left atrial area, resting E/e’, and exercise-induced increase in EF as independent determinants of BNP changes during follow-up.
In asymptomatic patients with preserved LV function and moderate AS, serial BNP may widely vary. Subclinical LV diastolic and systolic dysfunction frequently are present in patients with a progressive increase in BNP.
Prior studies have shown that, among patients with asymptomatic AS, a single measurement of BNP can correlate with aortic valve area, LV diastolic dysfunction, functional status, and symptomatic deterioration; and has been proposed to help improve risk stratification. This study suggests that a progressive increase in BNP can be correlated with subclinical LV systolic and diastolic dysfunction. Those observations seem sound. What is more open to interpretation is what to do with that information. Patients with moderate AS oftentimes have concomitant conditions that could affect LV systolic and diastolic function, including hypertension and coronary artery disease, and it is not yet clear that the observed associations between BNP and LV function necessarily are attributable to only moderate AS. Inasmuch as BNP might be a useful adjunct in the assessment of the asymptomatic patient with severe AS, it is not clear that BNP (as a static or serial measurement) necessarily should be used in isolation in timing intervention for asymptomatic AS.
Keywords: Echocardiography, Doppler, Coronary Artery Disease, Follow-Up Studies, Arterial Pressure, Stroke Volume, Diastole, Hypertension, Natriuretic Peptide, Brain
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