Natriuretic peptides in patients with diastolic dysfunction due to idiopathic dilated cardiomyopathy

Abstract

Aims. The degree of systolic dysfunction does not always correlate with functional impairment in patients with congestive heart failure. In contrast, diastolic dysfunction correlates well with functional impairment. In heart failure, both elevation of N-terminal proatrial natriuretic peptide and B-type natriuretic peptide are markers of a poor prognosis. Methods. We investigated 32 patients (26 male, 6 female; mean age 55 ± 2 years) with dilated cardiomyopathy and sinus rhythm. M-mode echocardiography and 2D-echocardiography were carried out in each patient. Pulsed-wave Doppler inflow signals were obtained and the following parameters were measured: maximal E wave and maximal A wave velocity, E/A ratio, E wave deceleration time, A wave deceleration time. Immediately after echocardiography blood samples were collected from patients in the supine position. N-terminal proANP and brain natriuretic peptide were measured using a radioimmuno assay. Results. The left ventricular ejection fraction was 34 ± 1%, the left ventricular end-diastolic diameter on M-mode echocardiography was 68 ± 1 mm, while left atrial diameter was 45 ± 1 mm. Univariate analysis revealed a significant correlation between both left atrial diameter and ejection fraction and N-terminal proANP and brain natriuretic peptide. All transmitral Doppler parameters showed a significant correlation with N-terminal proANP and brain natriuretic peptide. On forward stepwise regression analysis, left atrial diameter and ejection fraction were able to predict both N-terminal proANP and brain natriuretic peptide. However, of the diastolic parameters only the E/A ratio remained significant. Mildly symptomatic patients differed significantly from severely symptomatic patients in all Doppler parameters. Mildly symptomatic patients had significantly lower levels of N-terminal proANP (0.571 ± 0.079 vs 2.282 ± 0.340 nmol.l-1; P < 0.001) and brain natriuretic peptide (51 ± 14.8 vs 474.2 ± 86.8 pg.ml-1; P < 0.001). Conclusion. There is a close relationship between natriuretic peptides and diastolic Doppler parameters of left ventricular filling in patients with dilated cardiomyopathy. There is also a significant difference between patients with mild and severe functional impairment regarding both natriuretic peptides and transmitral Doppler parameters.