Effects of Beta-Blocker on Heart Rate Variability in Heart Failure with Preserved Ejection Fraction
Saleem S., Alkhodari M., Hadjileontiadis LJ., Khandoker AH., Jelinek HF.
Heart failure is characterized by sympathetic activation and parasympathetic withdrawal leading to an abnormal autonomic modulation. Beta-blockers (BB) inhibit overstimulation of the sympathetic system and are indicated in heart failure patients with reduced ejection fraction. However, the effect of beta-blocker therapy on heart failure with preserved ejection fraction (HFpEF) is unclear. This study investigated the effect of BB therapy on heart rate variability (HRV) features as a measure of risk of an abnormal cardiac event. ECGs of seventy-three patients with HFpEF > 55% were recruited. Fifty-six patients in the BB group and 17 patients in the without BB group. HRV analysis was performed for recordings between 6-10 am and 6-10 pm, which are times associated with increased risk of cardiac events. The result shows that RMSSD (p=0.011), HF power (p=0.012), and VLF power (p=0.047) were significantly higher during the 6 - 10 am interval. Sample entropy (p=0.016), and the novel fragmentation measures PIP (p=0.015), IALS (p=0.015) and PSS(p=0.008) were significantly higher between 6 - 10 pm. Beta-blocker therapy increases HRV measures in the HFpEF group depending on the feature investigated indicating an overall decreased risk of a cardiac event and a possibly beneficial effect of beta-blockers, especially during the morning hours that is characterized by a sympathetic surge.