Weak within-individual association of blood pressure and pulse wave velocity in hemodialysis is related to adverse outcomes.

Abstract

Hemodialysis patients have premature arterial stiffness, and the relationship between pulse wave velocity (PWV) and blood pressure (BP) may be different than in other hypertensives. Previous studies in such patients showed that when BP decrease is accompanied by PWV decrease the survival is improved. This study examines the prognostic role of the mean BP (MBP)-PWV association for cardiovascular outcomes and all-cause mortality in hemodialysis. A total of 242 hemodialysis patients underwent 48-h ambulatory BP monitoring with Mobil-O-Graph-NG and were followed for 33.17 ± 19.68 months. The within-individual MBP-PWV association (MBP, dependent and PWV independent variable) was evaluated using the β-coefficient value from simple linear regression analysis for each patient. The primary end-point was first occurrence of all-cause death, nonfatal myocardial infarction or nonfatal stroke. Secondary end-points were all-cause mortality, cardiovascular mortality and a combination of cardiovascular events. Higher quartiles of β-coefficients (indicating strong within-individual association of MBP with PWV) were related to greater cumulative freedom from the primary end-point (50.8, 60.0, 70.0 and 80.3% for quartiles 1-4, respectively; log-rank P = 0.001), better overall survival (60.7, 61.7, 73.3, 86.9%; log-rank P = 0.002) and better cardiovascular survival (78.7, 75.0, 81.7, 91.8% for quartiles 1-4; log-rank P = 0.044). The future risks of the primary end-point, all-cause and cardiovascular mortality and the combined outcome were progressively increasing with lower quartiles of β-coefficients, indicating patients with weak MBP-PWV association (hazard ratios for all-cause mortality 3.395; 95% confidence interval: 1.524-7.563, P = 0.003 for quartile 1 vs. quartile 4). Weaker within-individual MBP-PWV association, based on ABPM recordings, is associated with higher risk of death and cardiovascular events in hemodialysis. These findings support that arterial stiffness insensitive to BP changes is the underlying factor for adverse outcomes in these individuals.