Heart Rate Variability for Outcome Prediction in Intracerebral and Subarachnoid Hemorrhage: A Systematic Review

Area of Science:

• Neurology
• Cardiology
• Critical Care Medicine

Background:

• Intracerebral and subarachnoid hemorrhages are critical neurological events with significant mortality and morbidity.
• Predicting outcomes in these patients is crucial for guiding clinical management and resource allocation.
• Heart rate variability (HRV) is a non-invasive measure reflecting autonomic nervous system function, potentially offering prognostic insights.

Purpose of the Study:

• To systematically review and synthesize the existing clinical evidence on the association between heart rate variability and outcome prediction in patients with intracerebral and subarachnoid hemorrhages.
• To evaluate the utility of HRV in predicting functional outcome, cardiovascular complications, secondary brain injury, and mortality.

Main Methods:

• A comprehensive literature search was conducted across multiple databases to identify relevant studies.
• Nineteen significant studies investigating HRV in the context of hemorrhagic stroke were included in the systematic review.
• Analysis encompassed various HRV metrics derived from linear (time and frequency domains) and non-linear (entropy) approaches.

Main Results:

• Heart rate variability was consistently associated with poorer functional outcomes and increased mortality in patients with intracerebral and subarachnoid hemorrhages.
• The association between HRV and the prediction of secondary brain injury showed controversial or inconsistent results across studies.
• Evidence regarding the link between HRV and cardiovascular complications in this patient population was also found to be controversial.

Conclusions:

• Heart rate variability serves as a valuable prognostic marker for functional outcome and mortality following intracerebral and subarachnoid hemorrhages.
• Further research is warranted to clarify the role of HRV in predicting secondary brain injury and cardiovascular complications in these critically ill patients.