Heart rate adjusted heart rate variability reliable predictor of risk of sudden cardiac death

A new study published in BMC Cardiovascular Disorders suggests that similar exponential decay relationships between heart rate variability (HRV) measurements and heart rate (HR) were seen in subjects with varying sudden cardiac death (SCD) risks, however at varied rates of decay.

The predictive utility of heart rate variability for risk stratification of sudden cardiac death is yet unknown. Heart rate variability is a non-invasive method for the evaluation of cardiovascular autonomic function. Su-Peng Yan and colleagues looked at the effectiveness of the heart rate adjusted HRV (HRVI) for SCD risk stratification in people with various risks.

A total of 192 participants, comprising 88 healthy controls (low risk group), 82 people with hypertrophic cardiomyopathy (HCM), and 22 people with SCD, had their HRV measures examined (high risk group). Both a long-term and short-term study was used to explore the connection between HRV measures and HR. AUC and covariance of variation were used to assess the HRVI's performance (CV).

The key findings of this study were:

While the exponential power coefficients varied widely between groups, the majority of HRV measures exponentially degraded as HR increased. 

With a median AUC of 0.72[0.11], the HRVI measures distinguishing between patients at low, medium, and high risk. 

This was a significant improvement over the standard long-term and short-term HRV without correction. 

Compared to conventional short-term HRV measurements, the average CV of the HRVI metrics was also much lower (0.09 0.02 vs. 0.24 0.13, p 0.01).

In conclusion, similar exponential decay relationships between HRV measures and HR were seen in HCM patients with medium risk of SCD, although at different rates when compared to low risk healthy controls and high risk SCD patients. When assessed using the customized HR-based HRV adjustment approach, HCM patients had autonomic nervous dysfunction, which was manifested as reduced vagal activity and poor sympatho-vagal balance. The HRV measures with HR adjustment offer dependable and effective risk classification of SCD.

Reference: 

Yan, S.-P., Song, X., Wei, L., Gong, Y.-S., Hu, H.-Y., & Li, Y.-Q. (2023). Performance of heart rate adjusted heart rate variability for risk stratification of sudden cardiac death. In BMC Cardiovascular Disorders (Vol. 23, Issue 1). Springer Science and Business Media LLC. https://doi.org/10.1186/s12872-023-03184-0