Heart rate variability and functional outcome in ischemic stroke: a multiparameter approach

Area of Science:

• Cardiology
• Neurology
• Biomedical Engineering

Background:

• Heart rate variability (HRV) is a potential prognostic indicator in ischemic stroke.
• Assessing HRV in short-term ECG recordings presents challenges in parameter interpretation.
• Simultaneous analysis of heart rate, blood pressure, and respiratory rate aids in understanding HRV data and mitigating bias.

Purpose of the Study:

• To investigate the prognostic value of linear and nonlinear HRV parameters, blood pressure, and respiratory rate in ischemic stroke patients.
• To compare these parameters in relation to functional neurological outcomes at early (7th day) and later (90th day) stages.
• To explore the association between respiratory rate and stroke outcomes.

Main Methods:

• Seventy-five ischemic stroke patients underwent short-term ECG recordings.
• Linear and nonlinear HRV parameters, beat-to-beat blood pressure, and respiratory rate were assessed.
• Parameters were compared between patients with different functional neurological outcomes at 7 and 90 days.

Main Results:

• Lower complexity measures (Approximate, Sample, Fuzzy Entropy) were linked to poor early neurological outcomes.
• Poor 90-day outcomes correlated with higher high-frequency spectrum power and lower normalized low-frequency power.
• Low frequency/high frequency ratio negatively correlated with NIH Stroke Scale and mRS scores. Respiratory frequency significantly correlated with both early and long-term outcomes.

Conclusions:

• Complexity measures of HRV reflect neurological state's impact on heart rate dynamics.
• Linear HRV methods may offer long-term prognostic value.
• Respiratory rate is a significant early and long-term predictor of neurological outcome and warrants further investigation as a risk factor.