Kidney Function

Background: Noninvasive screening studies may identify hemodialysis (HD) patients at increased risk of sudden cardiac death. Interventions that improve the findings of such screening studies may reduce sudden cardiac death.Study Design: Randomized and controlled clinical trial.Setting & Participants: 59 HD patients were randomly assigned to an exercise training group (group A; 30 patients) or control group (group B; 29 patients).Intervention: Group A participated in a 10-month supervised exercise training program during the HD sessions (3 times weekly).Outcomes: Each risk factor separately and the composite risk score. Patients were considered high risk according to the criteria (aerobic capacity: peak oxygen consumption [Vo2peak] ≤ 14 mL/kg/min, left ventricular ejection fraction ≤ 30%, SD of normal RR intervals [SDNN] ≤ 70 milliseconds, positive T-wave alternans, or positive late potentials). Statistical analysis included a 2-group comparison of change scores and analysis of covariance adjusting for baseline.Measurements: At entry and end of the study, Vo2peak and left ventricular ejection fraction were estimated, heart rate variability was calculated (measurement of SDNN, mean RR intervals), and the ratio between low- (LF) to high-frequency (HF) components (LF/HF) and late potentials and T-wave alternans were detected.Results: Baseline measurements were similar between the 2 groups. At follow-up, 9 patients from group A and 20 from group B (P = 0.003) were considered high risk. The change in number of risk markers over time was significantly different between groups (−0.5 ± 0.7 in group A versus 0.07 ± 0.3 in group B; P < 0.001). Additionally, the change in Vo2peak over time was 3.5 ± 3.2 in group A and −0.2 ± 3.5 mL/kg/min in group B (P < 0.001), left ventricular ejection fractions were 3.4% ± 3.9% and 0.2% ± 7.7% (P < 0.05), SDNNs were 12.6 ± 16.3 and −1.1 ± 10.2 milliseconds (P < 0.001), and LF/HF ratios were 0.3 ± 0.4 and −0.1 ± 0.3 (P < 0.001), respectively. Change in numerical score of the signal-averaged electrocardiogram also was found to be statistically different (P < 0.05) between groups.Limitations: Clinical outcomes, including survival, were not assessed.Conclusions: Exercise training improves aerobic capacity and ameliorates some indicators of risk of sudden cardiac death in HD patients.

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