Heart rate variability as a digital biomarker for frailty in cardiovascular patients.

BACKGROUND

Frailty is a syndrome associated with age-related impairments in multiple organ systems, of which the autonomic nervous system plays a fundamental role. Measurement of heart rate variability (HRV) is a non-invasive method to evaluate the autonomic activity and gain insights into cardiovascular health and potentially, frailty. A few small studies have explored the relationship between HRV and frailty, with promising but conflicting results.

OBJECTIVE

To investigate the relationship between HRV and frailty among adult patients with cardiovascular disease.

DESIGN

A cross-sectional study was conducted using clinical data.

SETTING

Data were collected from an ambulatory cardiology clinic.

PARTICIPANTS

The cohort comprised 155 patients with a mean age of 67 years (44 % female).

MEASUREMENTS: HRV was assessed seated at rest for 2.5 min using a finger-based photoplethysmography (PPG) device. Frailty was assessed using the Clinical Frailty Scale (CFS), with a score ≥5 considered frail. Associations between HRV and frailty were examined using a Spearman correlation matrix and multivariable ordinal regression model. The LF/HF ratio (a frequency-domain measure reflecting imbalances between sympathetic and parasympathetic activity) was the primary HRV measure analyzed.

RESULTS

The prevalence of frailty was 15 %. Among all HRV measures, the LF/HF ratio was most closely correlated with frailty (p < 0.001). In the multivariable model, each 1 standard deviation decrease in LF/HF ratio was associated with a 1.1-point increase in CFS (95 % CI 0.7-1.6, p < 0.001). The optimal ROC cutoff at which the LF/HF ratio was associated with frailty is ≤ 0.37.

CONCLUSIONS

The LF/HF ratio is inversely correlated with the CFS and independently associated with frailty. Measurement of HRV is a promising technique to enrich existing frailty scales and assist in frailty assessments in an ambulatory cardiology clinic.