Relationship between heart rate variability and baseline clinical characteristics in super-aged patients with persistent atrial fibrillation

Objective To investigate the relationship between heart rate variability (HRV) and baseline clinical characteristics in super-aged (≥ 80 years old) patients with persistent atrial fibrillation (AF).

Methods A total of 108 super-aged patients with persistent AF were included in AF group, and 127 super-aged patients with sinus rhythm were included in control group. 24-hour ambulatory electrocardiogram monitoring was conducted to compare heart rate and HRV time-domain indicatorsstandard deviation of normal RR intervals (SDNN), standard deviation of the average of normal to normal intervals (SDANN) every 5 minutes throughout the recording, mean of the sum of the squares of differences between adjacent N-N intervals (RMSSD), average value of standard deviation of 5-minute NN intervals throughout the recording (SDNN index), heart rate variability (HRV) index, and percentage of NN intervals with differences greater than 50 ms accounting for the total number of NN intervals (PNN50). Clinical characteristics of AF patients were collected, and multiple linear regression analysis was used to explore the correlation between HRV time-domain indicators and heart rate and baseline clinical characteristics.

Results SDNN, RMSSD, HRV index, PNN50, and SDNN index were higher in the AF group than in the control group (P < 0.01). Multiple linear regression analysis showed that increased SDNN was significantly associated with hypertension (P=0.001), use of β-blockers (P=0.003), and slow heart rate (P < 0.001). Increased RMSSD wassignificantly associated with hypertension (P=0.040), use of β-blockers (P=0.002), and slow heart rate (P < 0.001). Increased HRV index was significantly associated with heart failure (P=0.003) and slow heart rate (P < 0.001). Increased PNN50 was significantly associated with slow heart rate (P=0.004). Increased SDNN index was significantly associated with the use of β-blockers (P=0.002) and slow heart rate (P < 0.001). Increased SDANN was significantly associated with hypertension (P=0.006), slow heart rate (P < 0.001), and use of dabigatran (P=0.021).

Conclusion There is a correlation between HRV and baseline clinical characteristics in super-aged patients with persistent AF, which may be due to the activity status of the autonomic nervous system.