Prognostic value of heart rate variability during long-term follow-up in chronic haemodialysis patients with end-stage renal disease.

BACKGROUND

Mortality is high in chronic haemodialysis patients with cardiovascular disease, and many of them die suddenly. Reduced heart rate variability (HRV) is an increased risk for death in various populations, but its prognostic value in haemodialysis patients remains uninvestigated.

METHODS

We analysed the associations between 24-h HRV measures and long-term mortality through a prospective follow-up of 31 chronic haemodialysis patients who underwent diagnostic coronary angiography.

RESULTS

Of the 31 patients, at baseline, seven had a previous myocardial infarction, five had a history of congestive heart failure and 14 had significant (> or =75%) coronary stenosis (four had multi-vessel stenosis). During follow-up for 60+/-5 months, 14 patients died, 11 of them suddenly. A left ventricular ejection fraction of <0.45, multi-vessel coronary stenosis, ventricular tachycardia on 24-h ECG and decreased/abnormal 24-h HRV (triangular index <22 and abnormal Poincaré plot) carried a univariate risk of all-cause death, while the risk of sudden death was only correlated with decreased HRV (standard deviation of normal-normal R-R interval <50 ms, triangular index <22 and ultra-low frequency power <8.7 ln(ms2)). Multivariate analysis revealed that a triangular index <22 was the best predictor of increased risk for both all-cause and sudden death (hazards ratio (95% CI); 8.1 (1.3-48.6) and 12.6 (1.3-126.4), respectively) and that the association was independent of cardiac function, macrovascular diseases, ventricular arrhythmias and cardiovascular risk factors. The 5-year mortality when the triangular index was > or =22 or <22 was 33 or 88% for patients with coronary artery disease and 0 or 50% for those without.

CONCLUSIONS

These results indicate that HRV has an independent prognostic value in chronic haemodialysis patients and identifies an increased risk for all-cause and sudden death.