Initiation of Dialysis Is Associated With Impaired Cardiovascular Functional Capacity

Abstract

Background The transition to dialysis period carries a substantial increased cardiovascular risk in patients with chronic kidney disease. Despite this, alterations in cardiovascular functional capacity during this transition are largely unknown. The present study therefore sought to assess ventilatory exercise response measures in patients within 1 year of initiating dialysis. Methods and Results We conducted a cross-sectional study of 241 patients with chronic kidney disease stage 5 from the CAPER (Cardiopulmonary Exercise Testing in Renal Failure) study and from the intradialytic low-frequency electrical muscle stimulation pilot randomized controlled trial cohorts. Patients underwent cardiopulmonary exercise testing and echocardiography. Of the 241 patients (age, 48.9 [15.0] years; 154 [63.9%] men), 42 were predialytic (mean estimated glomerular filtration rate, 14 mL·min^-1·1.73 m^-2), 54 had a dialysis vintage ≤12 months, and 145 had a dialysis vintage >12 months. Dialysis vintage ≤12 months exhibited a significantly impaired cardiovascular functional capacity, as assessed by oxygen uptake at peak exercise (18.7 [5.8] mL·min^-1·kg^-1) compared with predialysis (22.7 [5.2] mL·min^-1·kg^-1; P<0.001). Dialysis vintage ≤12 months also exhibited reduced peak workload, impaired peak heart rate, reduced circulatory power, and increased left ventricular mass index (P<0.05 for all) compared with predialysis. After excluding those with prior kidney transplant, dialysis vintage >12 months exhibited a lower oxygen uptake at peak exercise (17.0 [4.9] mL·min^-1·kg^-1) compared with dialysis vintage ≤12 months (18.9 [5.9] mL·min^-1·kg^-1; P=0.033). Conclusions Initiating dialysis is associated with a significant impairment in oxygen uptake at peak exercise and overall decrements in ventilatory and hemodynamic exercise responses that predispose patients to functional dependence. The magnitude of these changes is comparable to the differences between low-risk New York Heart Association class I and higher-risk New York Heart Association class II to IV heart failure.

Keywords: aerobic capacity; cardiopulmonary exercise testing; dialysis; end‐stage renal disease; oxygen uptake at peak exercise.

Figure 1. Differences in oxygen uptake at peak exercise (VO₂Peak), oxygen uptake at anaerobic threshold (VO₂AT), left ventricular mass index (LVMI), and peak workload between groups (unadjusted).

VO₂Peak, VO₂AT, LVMI, and peak workload in predialysis patients (blue), patients with a dialysis vintage ≤12 months (red), and patients with a dialysis vintage >12 months (green).

Figure 2. Differences in oxygen uptake at peak exercise (VO₂Peak), oxygen uptake at anaerobic threshold (VO₂AT), left ventricular mass index (LVMI), and peak workload between groups (adjusted).

VO₂Peak, VO₂AT, LVMI, and peak workload in predialysis patients (blue), patients with a dialysis vintage ≤12 months (red), and patients with a dialysis vintage >12 months (green). Comparisons were adjusted for age, diabetes, race, diuretic use, and intact parathyroid hormone levels.