Factors impacting on left ventricular hypertrophy in haemodialysis patients

Abstract

Left ventricular hypertrophy (LVH) and increases in large artery stiffness predict cardiovascular outcomes in patients with renal failure. What determines left ventricular mass index (LVMI) and large artery stiffness and the contribution toward LVH and large artery dysfunction is not entirely clear. Consequently, this cross sectional study was aimed at assessing the various factors impacting on LVH in haemodialysis (HD), to contribute toward our understanding of the pathophysiology of LVH and large artery dysfunction in 94 adult HD patients. Pre- and post-dialysis blood pressures (BPs) were determined over 12 sessions of dialysis and averaged. Pulse wave analysis performed at the carotid, femoral and radial arteries was employed to determine pulse wave velocity (PWV) and central augmentation index (AIc). Echocardiography was performed to determine left ventricular mass (LVM) indexed to body surface area (LVMI). Natriuretic peptides, procollagen type I c-peptide (PIP), c-terminal telopeptide of type I collagen (ICTP), matrix metalloproteinases and their inhibitors were studied. The prevalence of LVH was 72.8 % (67/92) .On multivariate analysis pre- (p≤ 0.005), post- (p<0.05) and averaged dialysis (p < 0.015) systolic BP were associated with LVMI and PWV. 24 hour (r = 0.260, p = 0.026), day (r = 0.247, p = 0.036), and night (r= 0.241, p = 0.042) systolic BP were not more closely associated with LVMI than the averaged dialysis systolic BP (r = 0.272, p = 0.010). Similarly 24 hour (r = 0.41, p = 0.0003), day (r=0.400, p = 0.0005), and night (r =0.416, p = 0.0003) systolic BP were not more closely associated with PWV than the post-dialysis systolic BP (r=0.39, p=0.0001) indicating that these BP measurements are as effective as 24-hour ambulatory BP in predicting cardiovascular target organ changes. No relationship between either PWV (r=-0.08), or AIc (r=-0.10) and LVMI, between PWV (r=-0.11), or AIc (r=0.03) and LV MWT was noted. IVCD was independently associated with LVMI (partial r adjusted for average dialysis SBP=0.27, p=0.014; partial r adjusted for 24-hour SBP=0.29, p=0.013), and LV mean wall thickness (p<0.01), but not with LV relative wall thickness (p=0.18), or LV end diastolic diameter (p=0.88). An association between IVCD and AIc (partial r adjusted for average dialysis SBP=0.21, p<0.05), but not PWV was noted. NT-proANP and NT-proBNP were independently associated with LVMI (p<0.0001) but neither were associated with IVCD independent of LVMI suggesting a close association with LVMI in HD. Serum concentrations of matrix metalloproteinases 1, 2 and 9, and their tissue inhibitors (1 and 2) were not associated with LVMI, remodelling or PWV and neither procollagen I nor the C-terminal telopeptide of type I collagen (ICTP) were associated with LVMI. Thus, factors impacting on LVH in this study were systolic BP, NT-proANP, NT-proBNP and IVCD.