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Study Review on Yoga for Heart Disease Finds Early Evidence of Benefit
Heart disease is the leading cause of death worldwide. There is growing evidence for the benefits of yoga for improving cardiovascular risk factors. Less is known about yoga’s effects for those with serious heart disease. A new systematic review of the research finds early evidence that yoga may reduce the incidence of various forms of heart disease, but concludes that more high quality studies are needed before making definitive recommendations.
Heart disease is the leading cause of death worldwide. There is growing evidence for the benefits of yoga for improving cardiovascular risk factors such as stress, depression, hypertension, hyperlipidemia and others for healthy adults. Less is known about yoga’s effects on health-related quality of life, exercise capacity, non-fatal cardiac events and mortality in those with serious heart disease.
A new systematic review published in European Journal of Preventive Cardiology finds that more high quality studies are needed before making definitive recommendations regarding the use of yoga as an adjunct intervention for those with severe cardiac illness.
A team of German researchers systematically reviewed all of the published yoga research up until October 2013 to ascertain yoga’s effectiveness in reducing “mortality, nonfatal cardiac events, exercise capacity, health-related quality of life, and modifiable cardiac risk factors” for those with a prior diagnosis of coronary artery disease, heart failure, cardiac dysrhythmia, cardiomyopathy or valvular heart disease.
Eligible studies included randomized trials (RCT’s, cluster-randomized trials or randomized cross-over-studies) in which a yoga intervention was compared to “usual care” or a non-pharmacological intervention. Studies were required to include at least 1 of 5 key outcomes: mortality, nonfatal cardiac events, modifiable cardiac risk factors (blood pressure and blood lipid levels), exercise capacity, and/or health-related quality of life (physical and/or psychological wellbeing). Yoga interventions of any frequency, length, duration or tradition and published in any language were reviewed.
Researchers examined the quality of the evidence and risk of bias (selection bias, performance bias, reporting bias etc.) using well-established, standardized measures of research quality.
Seven controlled studies (coronary heart disease , heart failure , and cardiac dysrhythmia ) with a total of 624 patients with heart disease were included in the final analysis.
Yoga for Coronary Heart Disease
Coronary artery disease (also known as ischemic heart disease and atherosclerotic heart disease) refers to a group of conditions that include myocardial infarction (heart attack), sudden coronary death, and stable and unstable angina (chest pain caused by reduced blood flow to the heart muscle).
All of the RCT’s assessing yoga for coronary heart disease originated in India. A total of 510 patients (mean age 51.5-58.75 years) with diagnosed coronary disease participated. While none of the 4 studies specified the type of yoga used, each included physical postures (asanas), breathing exercises (pranayama) and relaxation. Two of the 4 also included mediation and dietary advice.
Program frequency and duration ranged from 5, supervised yoga classes of 35-40 minutes in duration for 6 months, to a 4-day residential program with 60-90 minutes of daily home practice for a period of 14 weeks to 12 months. Control group format varied from “conventional medical therapy (dietary restriction and moderate aerobic exercise) to an un-described “control” group (2 studies).
Generally speaking, individuals in the yoga conditions experienced fewer nonfatal cardiac events, increased in exercise time, and had improved systolic and diastolic blood pressure and blood lipid levels (total cholesterol, LDL and triglycerides) when compared to non-yoga control groups. The groups did not differ on mortality.
Yoga and Heart Failure
Two RCT’s from the United States examined the effects of a yoga intervention on 59 patients (42.5-52.6% female, median age 52.8 years) with chronic heart failure. The 2 studies included predominantly African American (95%) participants (2.5% Caucasian and 2.5% Asian).
Both of these studies included Hatha yoga interventions of 60-70 minutes in duration, twice per week over 8 or 8-10 weeks (total 16 sessions). The yoga groups and no-intervention control group participants continued to receive “standard medical care” in both studies.
Results for both studies suggested significant group differences in exercise time and maximum oxygen consumption (V02 max: a measure of aerobic fitness). No significant differences in mortality or quality of life were detected, and neither study indicated any adverse events in the yoga group.
Yoga and Cardiac Dysrhythmia
Cardiac dysrhythmias refer to heartbeats that are irregular (arrhythmia), too fast (tachycardia) or too slow (bradycardia). They are caused by anomalies in electrical conduction in the heart.
One RCT conducted in the US examined the effects of a yoga intervention on 55 individuals (12.7% female, 92.7% Caucasian, mean age of 66.3 years), who had received an implantable cardioversion defibrillator for life-threatening arrhythmia.
Yoga group participants attended 8, weekly, 80-minute sessions that included yoga postures, breathing exercises, relaxation and meditation. The yoga and treatment as usual control groups also received “standard medical care” during the intervention.
Yoga group participants reported fewer nonfatal “device-treated ventricular events” compared to controls as well as lower reported shock anxiety at the end of the study.
More Research is Needed on Benefits of Yoga As Heart Disease Therapy
Authors of this systematic review conclude that there is “low” to “very low” evidence of yoga’s effectiveness for reducing cardiac events, mortality and modifiable cardiac risk factors, or increasing exercise capacity or health-related quality of life. “It should be noted that while the quality of evidence was generally graded low or very low, this should not be misinterpreted as absence of evidence,” caution the authors. “Low and very low evidence simply mean that further research is likely to have an important impact on the confidence in the results,” they conclude.
As is true for a great deal of yoga research, we are in the formative stages of understanding what works for whom and under what conditions. Further comprehensive and methodologically rigorous studies with sufficient sample sizes, randomization of participants, and adequately blind outcome assessments are needed to strengthen the evidence for yoga technologies as an ancillary treatment of symptoms for those with chronic heart conditions.
B Grace Bullock, PhD, E-RYT 500, is the Founding Director of the International Science & Education Alliance, a firm that provides strategic planning, research consultation and assessment design to support the empirically rigorous evaluation and sustainable implementation of programs in education, leadership, health and human services. Grace is an intervention scientist, psychologist, yoga educator and author who has worked extensively in integrated behavioral health settings. Her research, clinical practice, teaching and writing emphasize the incorporation of empirically supported psychotherapy with yoga therapy and mindfulness practices to relieve the symptoms of stress, trauma, anxiety, depression and other psychological illnesses, and to promote healthy relationships. She is Faculty at the Integrated Health Yoga Therapy therapist training program, and Professor of Yoga & Neuroscience at the Taksha University School of Integrative Medicine. Grace is the former Editor in Chief of the International Journal of Yoga Therapy and recipient of a Francisco J. Varela Research Award from the Mind & Life Institute. For more information contact Grace at firstname.lastname@example.org