Heart rate variability in chronic ischemic stroke: analysis during the sleep-wake cycle

Area of Science:

• Cardiology
• Neurology
• Autonomic Nervous System Research

Background:

• Autonomic nervous system (ANS) alterations post-ischemic stroke (IS) are not fully understood.
• Heart rate variability (HRV) offers a noninvasive method to evaluate autonomic function.

Purpose of the Study:

• To compare HRV parameters during the sleep-wake cycle in chronic ischemic stroke patients versus healthy controls.
• To investigate potential long-term autonomic dysfunction following ischemic stroke.

Main Methods:

• Retrospective analysis of 24-hour electrocardiogram (EKG) monitoring in 179 IS patients and 184 healthy subjects.
• Assessment of circadian variation using total autonomic activity index (VTAI) and parasympathetic activity index (VPAI).
• Statistical analysis included nonparametric tests, canonical discriminant analysis (CDA), and ANOVA.

Main Results:

• Healthy subjects showed higher HRV time and frequency domain parameters (SDNN, SDANN, LF) during wakefulness.
• During sleep, IS patients exhibited higher high-frequency (HF) band power and lower LF/HF ratio.
• IS patients demonstrated significantly reduced VPAI and VTAI, indicating diminished vagal activity.

Conclusions:

• Ischemic stroke patients exhibit diminished heart vagal activity, as evidenced by HRV.
• An imbalance in sympathetic and parasympathetic systems, particularly during sleep, is likely in IS patients.
• These autonomic imbalances may persist for months after the initial ischemic stroke event.