Exercise-based cardiac rehabilitation for people with implantable ventricular assist devices

Background

People with heart failure have a decreased capacity to undertake physical exercise, which has a negative impact on their health and quality of life. Recent research has shown that exercise-based cardiac rehabilitation (CR) may improve exercise capacity and quality of life in people with implantable ventricular assist devices (VADs), which are a type of mechanical pump that supports heart function. It was therefore considered important to systemically review randomised controlled trials (a type of study in which participants are assigned to a treatment group using a random method) to determine the benefits and harms of exercise-based CR in people with implantable VADs.

Purpose

To assess the effects of exercise-based CR in people with implantable VADs.

Methods

We searched the scientific literature for randomised controlled trials that assessed the effectiveness of exercise in people with heart failure who have implantable VADs by comparing participants receiving the exercise intervention with those receiving usual care, where the intervention consisted of a single type of exercise or more. We excluded participants with total artificial hearts. The evidence is current to 3 October 2017.

Results

We included only two randomised controlled trials and a total of 40 participants in this review. Exercise-based CR consisted of aerobic or resistance training or both three times per week for six to eight weeks. Two serious adverse events (i.e. participants who did not complete the study due to infections) occurred in one of the two trials. Furthermore, four participants in each study group required visits to the emergency department, although these participants did complete the study. Neither study evaluated the outcomes of death, rehospitalisation, heart transplantation, and cost. Due to the very low quality of the evidence, the effectiveness of exercise-based CR on quality of life was uncertain.

Quality of the evidence

We assessed the quality of the evidence for quality of life as very low due to the young age of the participants, Insufficient blinding, small number of participants, and imprecision because of wide range of confidence intervals. The effects of exercise-based CR for people with implantable VADs were not clear.

Conclusion

The current evidence is inadequate to assess the benefits and harms of exercise-based CR for people with implantable VADs compared with usual care. The amount of randomised controlled trial evidence was very limited and of very low quality. In addition, the training duration was very short term. High-quality randomised controlled trials are needed to collect data on events (death and rehospitalisation), patient-related outcomes (including quality of life), and cost.

Authors' conclusions: 

The evidence is currently inadequate to assess the safety and efficacy of exercise-based CR for people with implantable VADs compared with usual care. The amount of RCT evidence was very limited and of very low quality. In addition, the training duration was very short term, that is from six to eight weeks. Further high-quality and well-reported RCTs of exercise-based CR for people with implantable VADs are needed. Such trials need to collect data on events (mortality and rehospitalisation), patient-related outcomes (including quality of life), and cost-effectiveness.

Read the full abstract...
Background: 

Heart failure is the end stage of heart disease, and the prevalence and incidence of the condition is rapidly increasing. Although heart transplantation is one type of surgical treatment for people with end-stage heart failure, donor availability is limited. Implantable ventricular assist devices (VADs) therefore offer an alternative treatment to heart transplantation. Although two studies reported the beneficial effects of exercise-based cardiac rehabilitation (CR) on functional capacity and quality of life (QOL) by performing systematic reviews and meta-analyses, both systematic reviews included studies with limited design (e.g. non-randomised, retrospective studies) or participants with implantable or extracorporeal VADs.

Objectives: 

To determine the benefits and harms of exercise-based CR for people with implantable VADs.

Search strategy: 

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library, MEDLINE, Embase, PsycINFO, Conference Proceedings Citation Index-Science (CPCI-S) on Web of Science, CINAHL, and LILACS on 3 October 2017 with no limitations on date, language, or publication status. We also searched two clinical trials registers on 10 August 2017 and checked the reference lists of primary studies and review articles.

Selection criteria: 

Randomised controlled trials (RCTs) regardless of cluster or individual randomisation, and full-text studies, those published as abstract only, and unpublished data were eligible. However, only individually RCTs and full-text publications were included.

Data collection and analysis: 

Two review authors independently extracted outcome data from the included studies. We double-checked that data were entered correctly by comparing the data presented in the systematic review with the study reports. We had no dichotomous data to analyse and used mean difference or standardised mean difference with 95% confidence intervals (CIs) for continuous data. Furthermore, we assessed the quality of evidence as it relates to those studies that contribute data to the meta-analyses for the prespecified outcomes, using GRADEpro software.

Main results: 

We included two studies with a total of 40 participants in the review. Exercise-based CR consisted of aerobic or resistance training or both three times per week for six to eight weeks. Exercise intensity was 50% of oxygen consumption (VO2) reserve, or ranged from 60% to 80% of heart rate reserve. Two serious adverse events were observed in one trial, in which participants did not complete the study due to infections. Furthermore, a total of four participants in each group required visits to the emergency department, although these participants did complete the study. Summary scores from the 36-item Short Form Health Survey (SF-36) and the Kansas City Cardiomyopathy Questionnaire (KCCQ) were measured as quality of life. One trial reported that the KCCQ summary score improved by 14.4 points in the exercise group compared with 0.5 points in the usual care group. The other trial reported that the SF-36 total score improved by 29.2 points in the exercise group compared with 16.3 points in the usual care group. A large difference in quality of life was observed between groups at the end of follow-up (standardised mean difference 0.88, 95% CI -0.12 to 1.88; 37 participants; 2 studies; very low-quality of evidence). However, there was no evidence for the effectiveness of exercise-based CR due to the young age of the participants, high risk of performance bias, very small sample size, and wide confidence intervals, which resulted in very low-quality evidence. Furthermore, we were not able to determine the effect of exercise-based CR on mortality, rehospitalisation, heart transplantation, and cost, as these outcomes were not reported.

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