Different spectral components of 24 h heart rate variability are related to different modes of death in chronic heart failure

Aims: To assess whether analysis of heart rate variability (HRV) from 24 h Holter recordings provides information about the mode of death (pump failure vs. sudden death) in chronic heart failure (CHF). Methods and results: We analysed 24 h HRV in 330 consecutive CHF patients in sinus rhythm. Indices derived from time domain, spectral domain, and fractal analyses of 24 h automatic HRV were evaluated. Data from clinical assessment, echocardiography, right heart catheterization, exercise test, blood biochemical examination, and arrhythmia pattern were analysed. Patients were followed up for 3 years. Two simple multivariable models, both including 24 h spectral indices, were able to identify patients at higher risk of progressive pump failure and sudden death, respectively. Depressed power of night-time HRV (≤509 ms²) below 0.04 Hz [very low frequency (VLF)], high pulmonary wedge pressure (PWP ≥ 18 mm Hg) and low left ventricular ejection fraction (LVEF ≤ 24%) were independently related to death for progressive pump failure, while the reduction of power between 0.04 and 0.15 Hz at night (LF ≤ 20 ms²) and increased left ventricular end-systolic diameter (LVESD ≥ 61 mm) were linked to sudden mortality. Conclusion: Automatic spectral analysis of 24 h HRV provides independent risk indices related to mode of death in sinus rhythm CHF patients.