| Background. There is strong evidence that low heart rate variability is an important factor associated with risk for sudden cardiac death, cardiac morbidity, and all-cause mortality. Several studies have shown exercise, smoking cessation, relaxation, and psychological treatments increase HRV. Biofeedback may be another behavioral treatment that increases HRV in patients with CAD.; Methods. We attempted to determine if a course of cardio-respiratory biofeedback could increase HRV in 61 recovering coronary artery disease patients, 24 of whom were enrolled in the Healing Hearts program. All participants were randomly assigned to a treatment or control group. A total of 31 participants (treatment group) were treated individually for a total of six sessions. HRV, as measured by SDNN, was measured for both groups at weeks 1,6, and 18. Treatment sessions consisted of abdominal breathing retraining, heart and respiratory physiological feedback, and daily breathing practice.; Results. The SDNN QRS complexes were calculated. The ANOVA produced a highly significant time by treatment group interaction (p > .001), but no three-way interaction. The biofeedback group showed a significant increase in SDNN over time (Simple effects: p = .004) while the controls did not (p = .053), and actually showed a decreasing trend. Conclusion: The results suggest that a combination of HRV biofeedback and breathing retraining can increase HRV in patients with CAD. The improvement in HRV is independent of traditional cardiac risk factors. |
