The programme did not provide all of the benefits we had hypothesised, specifically; days in hospital and anxiety were not reduced. The study did not reach the sample size suggested by the power analysis, and therefore may have been underpowered to show differences. This may have been particularly so for the length of hospital stay, as the effect size in Arthur et al.'s study 
was atypically large. The probable reason why sample size was not reached was because the waiting times for heart surgery fell rapidly during the recruitment period, following a government initiative. Immediately prior to the study commencing, waiting times of over 6 months for non-urgent surgery were common. As the study concluded, the waiting times had fallen to 3 months. Taking into account the time it takes to recruit people, this may have reduced their motivation to participate, as surgery would seem close.
Arthur et al.'s exercise programme, which reduced days in hospital, was aimed at improving cardiovascular fitness 
. Another possibility for the lack of effect on length of hospital stay in the study reported here, where exercise was based on daily walks, is that the programme was not intensive enough to increase fitness to the point where it could affect recovery time. It should be noted that the small numbers of adverse events during the preoperative period demonstrates the safety of such a (graded) walking programme for patients awaiting surgery. In future a more intensive home-based exercise programme might be tried. It should also be noted that the patients recruited for this study were people on a non-urgent list, which limits the applicability of the study to more complex patients. However, it is possible that more complex patients could benefit from the programme, as the exercise component was based on individual prescription through setting patient-centred goals.
The HeartOp Programme did not affect anxiety whilst having a positive effect on depression which may be thought unusual; the two are usually moderately related and change together 
. It may be that the fact that patients were very close to the time of the operation meant that the intervention was swamped by the normal fears most patients have at this time. In part confirmation of this viewpoint, Arthur et al. also reported that their intervention had no effect preoperatively on anxiety 
, despite their intervention being compared with routine (no intervention) care.
The HeartOp programme did show positive effects preoperatively on depression and physical functioning, although the differences were small. It may be that changing the patient's misconceptions about heart disease, which is not part of usual nurse education procedures but which is a core component of the HeartOp Programme, helped. Many people with heart disease have misconceptions about their illness and how to cope with it. It has been found that people with heart disease who hold a number of common misconceptions are more anxious, depressed and physically limited [15,27]
, and that change in the number of misconceptions that people with angina hold is a greater predictor of physical functioning one year later than change in the frequency of angina.
These relationships between beliefs and outcome can be explained by Leventhal's Common Sense Model of Illness Behaviour 
, in which it is theorised that people build cognitive representations of their illness which engenders an emotional response. These parallel processes cause the adoption of certain coping behaviours which the person then appraises to assess their outcome. In this model, cardiac misconceptions can cause undue anxiety which provokes the adoption of avoidance coping with the consequence that fitness is lost and physical functioning reduced. The York Cardiac Beliefs Questionnaire is undergoing further testing at present in order to determine whether there are specific misconceptions about heart disease that predict poor outcome.
The significant differences between the two interventions were not maintained post-operatively. This is understandable as all patients who survived operation received a programme of advice about self-management during the immediate post-operative period, and all were offered a place (with a 74% take-up) on a post-operative cardiac rehabilitation programme. Thus the majority of patients received rehabilitation interventions with a similar focus to the HeartOp Plan in the post-operative period. As the benefits of cardiac rehabilitation are well-documented (for example, see the meta-analysis by Taylor et al. 
), it is not surprising that differences between the groups were not maintained. There is a potential that delivering prehabilitation to all patients awaiting cardiac surgery may offset some of the problems of people not accessing cardiac rehabilitation post-operatively. The uptake of post-operative cardiac rehabilitation in this study was well above that documented in a recent audit of UK cardiac rehabilitation programmes 
, and therefore it was not possible to assess the effect of the programme on people who do not attend post-operative rehabilitation. Further research is needed to assess this potential.
The HeartOp Programme appears to add worthwhile and cost effective benefits to a regime of nurse counselling and phone calls for patients awaiting coronary artery bypass surgery, and can be recommended as an additional tool for nurses working with patients in the pre-surgery period. The training to successfully facilitate the HeartOp Plan could be based on that used for a similar programme for people with angina — the Angina Plan. This training is delivered entirely by distance learning in a programme which takes between a week and a few months to complete — depending on the motivation of the student. This method has successfully trained over 800 facilitators, mainly in the UK but with some from countries across the world.