U-Shaped Association of the Heart Rate Variability Triangular Index and Mortality in Hemodialysis Patients With Atrial Fibrillation

Abstract

Background: Atrial fibrillation (AF) is common in hemodialysis patients and contributes to increased mortality. We aimed to examine heart rate variability triangular index (HRVI) in hemodialysis patients with AF as it has recently been reported to predict mortality in AF patients without kidney disease.Methods: A total of 88 patients on hemodialysis with a medical history of AF or newly diagnosed AF underwent 24-h electrocardiography recordings. The primary endpoint of cardiovascular mortality was recorded during a median follow up of 3.0 years. Risk prediction was assessed by Cox regression, both unadjusted and adjusted for the Charlson Comorbidity Index and the Cardiovascular Mortality Risk Score.Results: Median age was 76 years, median dialysis vintage was 27 months. Altogether, 22 and 44 patients died due to cardiovascular and non-cardiovascular causes. In 55% of patients AF was present during the recording. Kaplan-Meier plots of HRVI quartiles suggested a non-linear association between HRVI, cardiovascular, and all-cause mortality which was confirmed in non-linear Cox regression analysis. Adjusted linear Cox regression revealed a hazard ratio of 6.2 (95% CI: 2.1–17.7, p = 0.001) and 2.2 (95% CI: 1.3–3.8, p = 0.002) for the outer quartiles (combined first and fourth quartile) for cardiovascular and all-cause mortality, respectively. Patients in the first quartile were more likely to have sinus rhythm whereas patients in the fourth quartile were more likely to have AF.Conclusions: We found a U-shaped association between HRVI and mortality in hemodialysis AF patients. The results might contribute to risk stratification independent of known risk scores in hemodialysis AF patients.

Performance of heart rate adjusted heart rate variability for risk stratification of sudden cardiac death

“…Based on retrospective analyses of various risk stratification techniques, SCD was found to be associated with depressed HRV in 24-h recordings and can be predicted by some HRV metrics with relatively high accuracy [ 24 , 25 ]. For instance, Braunisch et al [ 26 ] observed a U-shaped association between HRVTI and mortality in hemodialysis atrial fibrillation patients. This result might contribute to risk stratification independent of known risk scores in these patients.…”

“…Indeed, Huikuri et al proved that an extremely lower HRV metric indicated true autonomic dysfunction, but a higher value of the metric might not always reflected more healthy autonomic function, it might be an indicator of an unhealthy and highly irregular pattern, such as erratic rhythms [ 9 ]. Shaffer et al also demonstrated that pathological conditions and cardiac conduction abnormalities might increase HRV metrics, and the increased HRV metrics were strongly associated with the increased risk of mortality [ 26 ]. Our results also confirmed that the methodologies used have a great impact on HRV analysis and can be used to explain the discrepancies of the clinical studies.…”