Evaluation of cardiac autonomic functions in patients with ankylosing spondylitis via heart rate recovery and heart rate variability

Objective: The aim of this study was to evaluate heart rate variability (HRV) and heart rate recovery (HRR) in otherwise healthy ankylosing spondlitis (AS) patients and control subjects. Methods: A total of 28 patients with AS and 30 volunteers matched for age and sex were enrolled. All subjects underwent HRV analysis, exercise testing (ET), and transthoracic echocardiography. HRR indices were calculated by subtracting first, second, and third minute heart rates (HR) from the maximal HR. Results: The AS and control groups were similar with respect to age (28.7 ± 5.7 vs. 29.3 ± 5.8 years), gender distribution [(male/female) 24/4 vs. 26/4], and left ventricular ejection fraction (LVEF) (63.8 ± 2.8% vs. 65.7 ± 3.6%). Mean HRR1 (24.8 ± 4.2 vs. 28.8 ± 5.5, P = 0.001) and HRR2 (42.0 ± 4.4 vs. 48.0 ± 6.3, P = 0.001) values were significantly higher in control group. SDNN, SDANN, RMSDD, and PNN50 significantly decreased; LF and LF/HF increased in AS patients compared with control subjects. Conclusions: Patients with AS has lower HRR and HRV indices with respect to normal subjects. Cardiac autonomic functions might be involved in AS patients even in patients without cardiac symptoms.