Does Exercise-Based Cardiac Rehabilitation Reduce Mortality and Hospitalization Rates After Heart Valve Surgery?: A Cochrane Review Summary With Commentary.

Abstract

The aim of this commentary is to discuss from a rehabilitation perspective the published Cochrane Review “Exercise-based cardiac rehabilitation for adults after heart valve surgery” by Abraham et al.1 (https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD010876.pub3/full), published by Cochrane Heart Group. This Cochrane Corner is produced in agreement with the American Journal of Physical Medicine and Rehabilitation by Cochrane Rehabilitation with views of the review summary authors in the “implications for practice” section. BACKGROUND Given the prevalence of heart valve disease is expected to increase with the aging of the world’s population,2,3 there is a need to improve healthcare quality for patients with heart valve disease. While effective valve surgery may be a cost-effective solution,2 rehabilitation after surgery is fundamental. Cardiac rehabilitation (CR) is one of the key areas in rehabilitation and challenging for rehabilitation professionals.4 Cardiac rehabilitation is a broad program, which should be individually tailored to the needs of patients with heart disease,5 and not only includes exercise but also addresses cardiovascular disease risk factors and provides patient education and social support.6 Cardiac rehabilitation is generally recommended for heart patients including mostly those after myocardial infarction and percutaneous coronary intervention as well as heart failure,7 although not routinely being recommended for heart valve surgery patients. It is suggested that it is reasonable and necessary in patients who have undergone heart valve surgery,8 and it is stated that it should be accessible for these patients.7 Similar to general CR principles, CR after cardiac valve surgery should include patient assessment, physical activity counseling, diet/nutritional counseling, tobacco cessation, psychosocial management, and exercise training, which is a key factor for CR.6,7 Regarding evidence-based practices, the evidence is scarce for patients who have undergone heart valve surgery or intervention as to the effectiveness of rehabilitation.3,9,10 A Cochrane Review1 searched for evidence to assess whether exercised-based CR is beneficial for patients after heart valve intervention and whether it has any harms. EXERCISE-BASED CARDIAC REHABILITATION FOR ADULTS AFTER HEART VALVE SURGERY (Abraham LN, Sibilitz KL, Berg SK, Tang LH, Risom SS, Lindschou J, Taylor RS, Borregaard B, Zwisler AD, 2021). WHAT IS THE AIM OF THIS COCHRANE REVIEW? The aim of this Cochrane Review was to evaluate the benefits and harms of exercise-based CR versus no exercise training in adults undergoing heart valve surgery or repair, whether with percutaneous or surgical procedure. WHAT WAS STUDIED IN THE COCHRANE REVIEW? The population addressed were adults 18 yrs or older without gender or ethnicity restrictions who had undergone heart valve surgery (i.e., heart valve replacement or heart valve repair) by percutaneous or surgical procedure for any valvular heart disease. The interventions studied were exercise-based CR interventions either supervised or unsupervised in a variety of settings, such as inpatient, outpatient, home, or community settings, the exercise training and component aiming to increase exercise capacity and including a postoperative element, independent of whether a psychoeducational intervention was accompanied and the length, intensity, or content of the intervention. The interventions were compared with no intervention, treatment as usual, and any other form of CR program (i.e., without physical exercise component). Primary outcomes studied were all-cause and cardiovascular mortality, all-cause hospitalization, and health-related quality of life reported with generic or disease-specific validated scales. Secondary outcomes were exercise capacity, serious adverse events, return to work, as well as the expenses and cost-effectiveness. Outcomes could be evaluated at the end of the intervention and at the longest follow-up available. SEARCH METHODOLOGY AND UP-TO-DATENESS OF THE COCHRANE REVIEW? The review authors searched for studies without language restrictions that had been published until January 10, 2020, in Cochrane Central Register of Controlled Trials, Database of Abstracts of Reviews of Effectiveness, Cumulative Index to Nursing and Allied Health Literature plus with Full Text Latin American Caribbean Health Sciences Literature in English, Conference Proceedings Citation Index-S on Web of Science, and those published up to January 9, 2020, in MEDLINE/Epub Ahead of Print and Ovid MEDLINE In-Process and Other Non-Indexed Citations and Daily, Embase Classic and Embase (Ovid), as well as PsycINFO (Ovid, until the first week of January). They also searched for clinical trials registries, including ClinicalTrial.gov, International Standard Randomized Controlled Trials Number Registry, and World Health Organization International Clinical Trials Registry Platform on May 15, 2020. WHAT ARE THE MAIN RESULTS OF THE COCHRANE REVIEW? The review included six studies involving 364 participants, four of which including those with aortic valve replacement, one including those with mitral valve replacement, and another including all cardiac valve replacements. Most study subjects were men in the four studies, equal to women or slightly less in the other two studies with mean age ranging from 31 to 82 yrs. The duration of follow-up ranged from 3 to 24 mos across the studies. Study participants were offered combined aerobic and resistance training after surgery two to three 20- to 60-min sessions per week, except for one study where a psychological intervention and exercise training were administered before surgery, the total duration of training varying from approximately 1 mo to more than 3 mos. One study included a program that lasted up to 4 hrs a day. The review shows the following: A. Primary outcomes All-cause mortality (2 studies, 131 participants) Reported deaths were four versus five in the exercise-CR and control groups, respectively, with a risk ratio of 0.83 (95% confidence interval [CI] = 0.26–2.68) based on very low certainty evidence. ii. Cardiovascular mortality (this outcome was not reported by any of the studies) iii. All-cause hospitalizations (1 study, 122 participants) Reported hospitalizations were one versus zero in the exercise CR and control groups, respectively, with a risk ratio of 2.72 (95% CI = 0.11 to 65.56) based on very low certainty evidence. iv. Health-related quality of life There were two studies reporting health-related quality of life as measured using 12- or 36-Item Short-Form Health Survey questionnaires at the end of the intervention and at the longest follow-up. Postintervention (2 studies, 150 participants, follow-up range of 2–3 mos) No difference was observed between exercise-based CR and control groups in either mental (mean difference [MD] = 1.28, 95% CI = −1.60 to 4.16) or physical component (MD = 2.99, 95% CI = −5.24 to 11.21) subscores, based on very low-quality evidence for both components. b. At the longest follow-up (2 studies, 139 participants, follow-up range of 6–24 mos) No difference was observed between exercise-based CR and control groups in either mental (MD = −1.45, 95% CI = −4.70 to 1.80) or physical component (MD = −0.87, 95% CI = −3.57 to 1.83) subscores based on very low certainty evidence for both components. B. Secondary outcomes Exercise capacity Postintervention A moderate increase was observed in the exercise-CR group in comparison with the control group as presented in maximal measures, which is composed of all peak exercise capacity data across trials with a standardized mean difference of 0.38 (95% CI = 0.15 to 0.61) in five studies involving 194 participants and also as presented in VO2 max with an MD of 2.38 ml/kg/min (95% CI = 0.36 to 4.40) in four studies involving 250 patients, however, not in submaximal 6-min walk test (MD = −3.89 m, 95% CI = −58.72 to 50.95) in three studies with 167 patients. b. At the longest follow-up A moderate increase was observed in favor of exercise in maximal measures with a standardized mean difference of 0.37 (95% CI = 0.15 to 0.61) in five studies with 284 patients, however, in neither VO2 max (MD = 1.53 ml/kg/min, 95% CI = −0.44 to 3.50) in four studies involving 240 patients nor in 6-min walk test (MD = −25.48 m, 95% CI = −103.04 to 52.08) in three studies with 158 patients. ii. Adverse events As assessed in four studies involving 326 patients, the percentage of serious adverse events was 7.3% versus 6.8% in the intervention and control groups, respectively, showing no group difference with a risk ratio of 1.07 (95% CI = 0.50 to 2.27). iii. Return to work As assessed in only one study with 44 patients at 12 mos, the percentage of those returning to work was 19% versus 35% in the exercise-based CR and control groups, respectively, showing no group difference with a risk ratio of 1.24 (95% CI = 0.86 to 1.79). iv. Expenses and cost-effectiveness Exercise-based CR was reported to be cost-effective with a probability of 75% and greater based on cost data in one study. WHAT DID THE AUTHORS CONCLUDE? The authors concluded that the evidence for exercise-based CR’s impact on all-cause mortality, all-cause hospitalizations, and health-related quality of life was of very low certainty. As a result, although it is predicted to be beneficial in terms of increase in short-term exercise capacity, the available data are insufficient to draw definitive conclusions regarding the effects of exercise-based CR on previously mentioned outcomes. WHAT ARE THE IMPLICATIONS OF THE COCHRANE EVIDENCE FOR PRACTICE IN REHABILITATION? Although exercise-based CR seems to be potentially usable in increasing short-term exercise capacity and may positively affect return to work after heart valve surgery,7 we do not know about its effects on all-cause mortality, hospitalizations, and health-related quality of life. This situation urges rehabilitation professionals with expertise in cardiac rehabilitation to be involved in future research with robust methodology. Of note, it is important to consider aspects related to COVID-19 pandemic regarding rehabilitation after cardiac valve surgery from two perspectives. One is the problems encountered as to the delivery of rehabilitation during the pandemic, not sufficiently being offered, and the need of evolution of different models of delivery, such as home-based models.11 On the other hand, from the mechanism-related aspect, there are grounds to speculate that SARS-CoV-2 may attack cardiac valves with the potential to damage cardiac valves warranting examination of heart valves of individuals having recovered from COVID-19,12 with implications of extended need for rehabilitation. Although home-based cardiac rehabilitation has been shown to be as effective as center-based rehabilitation in improving clinical and health-related quality of life outcomes after myocardial infarction or revascularization or in heart failure patients,13 no such evidence is yet available for cardiac rehabilitation after heart valve surgery. Future research may focus on innovative models of delivery of rehabilitation after cardiac valve surgery. Other rehabilitation relevant issues include those related to the content of CR programs after heart valve surgery. Although the current review1 explored exercise-based CR, more comprehensive programs may be investigated as to effectiveness. It was stated that CR interventions after valve surgery may also include respiratory physiotherapy, nutritional counseling, tobacco cessation, as well as addressing medical problems, such as high blood pressure, diabetes, and hyperlipidemia, and provide comprehensive information on endocarditis prophylaxis.7,8 In addition, individuals having undergone heart valve surgery were reported to benefit from psychological assessment, including the assessment of mental and existential issues and information on recovery process.14 Furthermore, when conducting research on rehabilitation, it is imperative to consider appropriate terminology. A recent definition of rehabilitation for research purposes proposed by Cochrane Rehabilitation to support the conduct of primary research could be helpful in this regard. According to this definition, to be considered as rehabilitation, the process needs to fulfill all definition items, which include being multimodal, person centered, collaborative with interventions addressing body structures, functions, and activities, participation relevant to capacity, as well as contextual factors relevant to performance with the goal of optimizing functioning in disabling health conditions.15 Having stated the definition of rehabilitation for research purposes, it is apparent that it is also important to determine functioning outcomes with appropriate outcome measures. The International Classification of Functioning, Disability and Health-based instruments16 could be helpful in depicting the whole picture of functioning of an individual. In summary, more studies are still needed that are designed from a rehabilitation perspective and evaluate the functional outcomes of cardiac rehabilitation after heart valve surgery with appropriate outcome measures.