Increased arterial stiffness and heart rate variability over time in heart transplant recipients: A cross-sectional study using peripheral arterial tonometry

Background

Arterial stiffness represented by Augmentation index (AIx) and heart rate variability (HRV) are established predictors of cardiovascular risk in heart transplant (HTx) recipients. However, the relationship between AIx and HRV in this population remains insufficiently explored, and factors such as time after transplantation may influence both metrics.

Objective

The purpose of this study was to evaluate vascular function through Aix and HRV parameters in HTx patients, both assessed by peripheral arterial tonometry (PAT).

Methods

A cross-sectional study was conducted with 35 adults aged 18 to 65 years, HTx ≥ 6 months after surgery, with stable clinical condition and no changes over the last 3 months of immunosuppressive treatment. AIx and HRV were assessed using PAT.

Results

Participants were categorized into 2 groups based on AIx values: high AIx (n = 19, AIx > −5%) and low AIx (n = 16, AIx ≤ −5%). The high AIx group had a significantly longer time after transplantation (p = 0.00). HRV analysis revealed that the standard deviation of all normal NN intervals (SDNN, p = 0.044), and lower frequency to high-frequency ratio (LF/HF, p = 0.034) were significantly higher (p = 0.03) and HR was significantly lower (p = 0.04) in the high AIx group compared to low AIx.

Conclusions

Arterial stiffness assessed by PAT was higher in patients with a longer time after heart transplantation. Similarly, HRV indices, which reflect several cardiovascular health conditions, such as SDNN and sympathovagal balance (LF/HF ratio) were higher in the group with higher arterial stiffness in individuals after heart transplantation.