Abstract
Decreased HRV has been consistently associated with increased cardiac mortality and morbidity in HF patients. The aim of this study is to determine if a 6-week course of heart rate variability (HRV) biofeedback and breathing retraining could increase exercise tolerance, HRV, and quality of life in patients with New York Heart Association Class I-III heart failure (HF). Participants (N = 29) were randomly assigned to either the treatment group consisting of six sessions of breathing retraining, HRV biofeedback and daily practice, or the comparison group consisting of six sessions of quasi-false alpha-theta biofeedback and daily practice. Exercise tolerance, measured by the 6-min walk test (6MWT), HRV, measured by the standard deviation of normal of normal beats (SDNN), and quality of life, measured by the Minnesota Living with Congestive Heart Failure Questionnaire, were measured baseline (week 0), post (week 6), and follow-up (week 18). Cardiorespiratory biofeedback significantly increased exercise tolerance (p = .05) for the treatment group in the high (≥31%) left ventricular ejection fraction (LVEF) category between baseline and follow-up. Neither a significant difference in SDNN (p = .09) nor quality of life (p = .08), was found between baseline and follow-up. A combination of HRV biofeedback and breathing retraining may improve exercise tolerance in patients with HF with an LVEF of 31% or higher. Because exercise tolerance is considered a strong prognostic indicator, cardiorespiratory biofeedback has the potential to improve cardiac mortality and morbidity in HF patients.
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Notes
No statistical analyses were conducted when determining the LVEF category split. The investigators had no knowledge of the statistical outcomes based on the LVEF divisions prior to conducting the statistical analyses outlined below.
For Cohen’s d an effect size of 0.2–0.3 is considered a small effect size, 0.5 is considered a medium effect size, and 0.8 to 1.0 a large effect size (Cohen 1988).
Cohen (1973) considers .01–.05 a small magnitude of effect, .06–.14 a medium magnitude of effect, and ≥.15 as a large magnitude of effect.
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Acknowledgments
We would like to thank Carlos Fayard, Ph.D. at Loma Linda University School of Medicine for his contributions and support of this research. We would also like to thank the staff in the Cardiomyopathy Clinic in the International Heart Institute at Loma Linda University Medical Center, Bonnie Huiskes, Sharon Fabbri, Denise Petersen, Donna Herman, Tiffany White, Donna Schmidt, Loretta Koptzke, Ellen Kiger, Trisha Aguilar, and Silvia Westrom, who were always available to answer questions, assist with numerous study details, provide necessary patient care to study participants, and somehow miraculously find the space in small and extremely busy clinic. Lastly, we would like to thank Eva Stuart and Donna Gilligan at the Scripps Center for Integrative Medicine for their dedication and input.
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Swanson, K.S., Gevirtz, R.N., Brown, M. et al. The Effect of Biofeedback on Function in Patients with Heart Failure. Appl Psychophysiol Biofeedback 34, 71–91 (2009). https://doi.org/10.1007/s10484-009-9077-2
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DOI: https://doi.org/10.1007/s10484-009-9077-2