Objectives: To determine if cardiorespiratory biofeedback increases heart rate variability (HRV) in patients with documented coronary artery disease (CAD).
Background: Diminished HRV has been associated with increased cardiac morbidity and mortality. Evidence suggests that various lifestyle changes and pharmacologic therapies can improve HRV. The objective of this study was to determine if biofeedback increases HRV in patients with CAD.
Methods: Patients with established CAD (n = 63; mean age, 67 years) were randomly assigned to conventional therapy or to 6 biofeedback sessions consisting of abdominal breath training, heart and respiratory physiologic feedback, and daily breathing practice. HRV was measured by the standard deviation of normal-to-normal QRS complexes (SDNN) at week 1 (pretreatment), week 6 (after treatment), and week 18 (follow-up).
Results: Baseline characteristics were similar for the treatment and control groups. The SDNN for the biofeedback and control groups did not differ at baseline or at week 6 but were significantly different at week 18. The biofeedback group showed a significant increase in SDNN from baseline to week 6 (P <.001) and to week 18 (P =.003). The control subjects had no change from baseline to week 6 (P =.214) and week 18 (P =.27).
Conclusions: Biofeedback increases HRV in patients with CAD and therefore may be an integral tool for improving cardiac morbidity and mortality rates.