Circulating N-terminal brain natriuretic peptide precursor and endothelin levels in patients with syndrome X and left bundle branch block with preserved systolic function

Background: Deterioration of left ventricular function during follow-up was reported in some patients with syndrome X and concomitant left bundle bran ch block. The patients with syndrome X and left bundle branch block has bee n frequently presented with elevated Endothelin-l (ET-1) level while brain natriuretic peptide (BNP) (a sensitive marker of left ventricular dysfuncti on) has not been measured in patients with syndrome X. Methods: The purpose of the present study was to assess left ventricular diastolic function, le vels of N-terminal Brain Natriuretic Peptide (NT-proBNP) precursor and bioc hemical parameters of endothelial function in patients with syndrome X comp licated by left bundle branch block but preserved left ventricular systolic function (group A, n=8). The echocardiographic and neurohormonal measures in these patients were compared to those in patients with syndrome X withou t left bundle branch block (group B. n = 13), and controls (group C, n=15). Results: At rest and after exercise the serum concentration of NT-proBNP w as significantly higher in group A than in the controls (at rest: 232 +/- 9 6 vs. 133 +/- 23 fmol/ml, P=0.03, after exercise: 313 +/- 96 vs. 180 +/- 33 fmol/ml. P=0.02). The highest concentration of endothelin-1 was also found in group A. being significantly higher than in the controls (6.81 vs. 4.52 pg/ml. P <0.05). Mitral how abnormalities were detected in left bundle bra nch block patients. Accordingly, the lowest E/A ratio was in group A acid i t differed significantly from that in group C (0.85 vs. 1.1, P <0.05). E/A ratio inversely correlated with plasma NT-proBNP concentration in patients with left bundle branch block (r = -0.48, P=0.02). Conclusions: Elevated NT -proBNP and endothelin-l plasma concentrations were demonstrated in patient s with syndrome X complicated by left bundle branch block even when left ve ntricular systolic function was still preserved. In this subgroup the magni tude of left ventricular diastolic dysfunction correlated with the increase of BNP level which reflects neurohormonal activation. (C) 2001 Elsevier Sc ience Ireland Ltd. All rights reserved.