Cardiac rehabilitation after transcatheter aortic valve implantation: Growing needs in a growing population

Among the numerous innovative technical developments within cardiology in recent years, transcatheter aortic valve implantation (TAVI) certainly holds a leading position. Subsequent to its first application in humans by Cribier et al. in 2002,1 it was originally intended as an alternative treatment procedure for elderly patients with severe aortic stenosis who would otherwise have an inadequately increased perioperative mortality risk during surgical aortic valve replacement (SAVR). Following the landmark PARTNER trials,2,3 numerous studies and registries have reported a superior outcome of the TAVI procedure compared with conservative therapy, as well as equal outcomes compared with SAVR.4–7 According to recent studies, these positive findings can be maintained over the long term8 and appear to be valid also for patients with lower perioperative mortality risk.9 It can thus be expected that the number of patients undergoing TAVI instead of SAVR will continue to rise exponentially in the near future. However, aortic stenosis is primarily a disease of the elderly, frail patient, and it is apparent that TAVI patients require a more intensive and prolonged cardiac aftercare than many other cardiac diseases.10 The TAVI procedure itself is associated with significant clinical improvements as compared with conservative therapy,2 but the specific nature of the TAVI population requires a particular focus on strategies addressing their reduced mobility, their increased multimorbidity and frailty.10 These outcomes are of at least equal relevance to clinical endpoints and should thus be considered when evaluating the effetcs of cardiac rehabilitation. In recent years, several observational studies have analysed the effect of cardiac rehabilitation programmes in patients after TAVI, either within the population itself or as compared with patients after SAVR.11–13 The majority of these studies have focused on established outcomes referring to the issues mentioned above such as the 6 minute walking distance (6MWD) or various measures of frailty or quality of life such as the Barthel index. However, outcome measures differ between these studies, and sample sizes are low, limiting their comparability and reproducibility. Therefore, the results represent at best preliminary findings providing initial evidence on how to design and perform adequate rehabilitation programmes. To overcome these limitations, Ribeiro et al. now provide a first summary of these preliminary observations in their systematic review and meta-analysis, published in this issue of the journal.14 They included five studies with a total of 292 TAVI and 570 SAVR patients undergoing inpatient cardiac rehabilitation over approximately 3 weeks. Programmes included aerobic and resistance exercise and/or inspiratory muscle training, but detailed protocols were not provided. Rehabilitation proved to be safe in not inducing increased adverse clinical event rates associated with elements of the programmes. Among both TAVI and SAVR patients, significant improvements in 6MWD and the Barthel index were observed, although the latter was only reported in two of the trials included. No differences were observed when comparing TAVI and SAVR patients, but heterogeneity was high among studies. Given the low number of studies included as well as their retrospective and observational design, this meta-analysis again certainly represents a very preliminary evaluation of the outcomes of cardiac rehabilitation after TAVI. Due to the heterogeneity of the outcomes reported, Ribeiro et al. had to focus on 6MWD and the Barthel index, as these were the only parameters that were evaluated by the majority of studies. In contrast, data on exercise capacity assessed by peak oxygen uptake or on quality of life assessed by established questionnaires were scarce and could therefore not be implemented into the meta-analysis. As many TAVI patients may not be able to undergo cardiopulmonary exercise testing, at least at the early stage of rehabilitation, 6MWD is certainly an important outcome that has been shown to improve shortly after the procedure independent of subsequent cardiac rehabilitation.15 However, when evaluating exercise-based programmes, peak oxygen uptake would represent a better measure of physical fitness and should thus be evaluated in all TAVI patients who are physically able to perform exercise testing. Moreover, the Barthel index may be an acknowledged parameter of physical integrity, but it is not well represented in the international literature when assessing the frailty status in cardiovascular disease.16 Regarding quality of life, the Kansas City cardiomyopathy questionnaire and the short form 12 (SF-12) health survey have, among others, been applied to TAVI populations in previous studies,17,18 and should be implemented into future research on outcomes after rehabilitation. These approaches have very recently already been realised by Eichler et al.,19 who observed significant improvements in SF-12 physical and mental subscales, associated with a reduced multicomponent frailty index in a cohort of TAVI patients after an inpatient cardiac rehabilitation programme. As stated above, the TAVI procedure itself is already associated with improvements in these parameters.18,20 Therefore, it is of utmost importance for the cardiac rehabilitation community to provide similar data in order to establish evidence-based programmes that prove to be superior to usual cardiac aftercare. This is also important with respect to cost issues. Future studies should also focus on the safety of exercise programmes with respect to established echocardiographic parameters of prosthesis function.21 Furthermore, continuing outpatient programmes might be necessary to maintain or further improve parameters of physical function and quality of life, allowing the patients to stay within their familiar environment and to follow their daily activities as long as possible. Finally, there is a need for randomised trials on rehabilitative programmes compared with usual aftercare subsequent to TAVI. These studies should not only evaluate the impact of cardiac rehabilitation on the outcomes mentioned above, but also on clinical endpoints such as morbidity and mortality. Preliminary data from a randomised pilot trial on a prolonged exercise intervention after TAVI have recently been published and may aid in designing larger trials comparing exercise-based programmes with usual care.22 The SPORT:TAVI trial was a pilot trial randomly assigning 30 patients after TAVI to either 8 weeks of supervised aerobic and resistance exercise or to a non-exercising control group. The exercise intervention resulted in significantly improved exercise capacity, muscular strength and several parameters of quality of life as assessed by the questionnaires mentioned above. Exercise was also safe with respect to prosthesis function and could be performed without adverse events even by nonagenarians. In summary, the systematic review and meta-analysis performed by Ribeiro et al.14 underlines the increasing significance of cardiac rehabilitation programmes in the rapidly growing TAVI population. However, it still represents a preliminary analysis in focusing on only two parameters that do not reflect the heterogeneous nature of these patients. Apart from further collecting observational data, randomised trials are warranted in order to establish evidence-based programmes that significantly improve the clinical outcome of TAVI patients beyond the procedure itself. The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. The author(s) received no financial support for the research, authorship, and/or publication of this article.