Physical inactivity after valve surgery is associated with increased mortality. Where do we go from here?

Nowadays, there is irrefutable evidence for the health benefits of physical activity on the cardiovascular system in primary and secondary prevention.1 This was only recently underscored once again in a meta-analysis by Cheng et al.2 Pooled analysis of 44 cohort studies comprising over 1.5 million participants found hazard rates of cardiovascular mortality for moderate and high leisure-time physical activity of 0.77 (95% confidence interval (CI) 0.74–0.81) and 0.73 (95% CI 0.69–0.77), respectively. Furthermore, a linear negative correlation was found with higher volumes of physical activity being associated with lower risk, regardless of age, gender and the presence of cardiovascular disease. The majority of these studies established this relationship using a single evaluation of physical activity. Yet, major life transitions such as transition to adulthood, job changes and retirement, but also illness, are periods when physical activity habits may be sensitive to change. Therefore, more recent studies are focusing on changes in physical activity and their impact on mortality. In the current issue of the European Journal of Preventive Cardiology, Kim et al.3 add further evidence for the beneficial effects of physical activity in the long-term management of patients following valve surgery. In this retrospective study, which was performed using the Korean National Health Insurance Service database, 6587 adult patients (55.6% men, mean age 60.9 years) who underwent valve surgery were followed up for a median duration of 2.8 years (Q1–Q3: 1.4–4.2 years) after surgery. Demographic characteristics and physical activity were evaluated before and following surgery. The authors used a three-item self-administered questionnaire, previously developed and validated by Smith et al.,4 to classify patients as highly active, adequately active or inactive. Mortality was defined as all-cause death with a maximum follow-up period of 5 years post-surgery. First of all, they found that half of the patients (49.5%) were physically inactive after surgery.3 Among a cohort of 742 patients who received heart valve surgery in Denmark, Lund et al. documented similar low levels of physical activity.5 Regrettably, among the subjects who were physically active before the heart valve surgery, 39% became physically inactive postoperatively.3 Inactivity after heart valve surgery was associated with a 35% higher risk of long-term mortality (95% CI 1.04–1.77). When looking at changes in physical activity levels, the active patients that became inactive after surgery showed a trend of 47% (95% CI: 1.08–1.83) higher risk of mortality than the group that remained active. The group that was inactive at both time points showed the highest mortality rate with a 69% (95% CI 1.19–2.40) higher mortality than the active/active group. The authors found no significant difference between the inactive/active group and the active/active group. In accordance to these results Lahtinen et al.6 showed earlier that after adjustment for major confounders (e.g. age, gender, diabetes, left ventricular ejection fraction, smoking, …) patients with coronary artery disease who remained inactive or became inactive during a 2 year follow-up period had 4.9- and 2.4-fold risk for cardiac death respectively compared with patients who remained active. They also found that the change from sedentary behaviour towards at least irregular physical activity involved risk that did not differ significantly from maintenance of physical activity.6 Of course, one can comment on the cross-sectional design of the study, which does not allow causal inferences. Moreover, a large number of patients were not included in the study by Kim et al. due to the limitations inherent to a retrospective study design. This could have resulted in selection bias. Furthermore, the use of self-reported subjective questionnaires for physical activity comes with other potential for bias.7 Yet, despite its limitations, the present study should be considered as the umpteenth wake-up call documenting that a large group of patients are still insufficiently active after cardiac surgery, despite the class IA recommendation for cardiac rehabilitation.8 Moreover, a significant proportion of patients who were active become inactive following surgery, which is very unfortunate. So, where do we go from here? Mounting evidence highlights that participation in a comprehensive cardiac rehabilitation programme in patients after valvular surgery results in increased fitness through a structural exercise programme,9–11 although long term benefits need to be documented further and the optimal characteristics of a training programme for this specific population is to be investigated. Yet, a Class IA recommendation does not necessarily result in high numbers of patients being referred or taking up cardiac rehabilitation. Indeed, the low number of patients with an active lifestyle following valve surgery is in line with the observations of the latest EUROASPIRE V study.12 Furthermore, cardiac rehabilitation should result in patients taking up a healthy active lifestyle and maintaining this preferably lifelong. A recent meta-analysis by Dibben et al.13 showed that there is only moderate evidence of an increase in physical activity with cardiac rehabilitation participation compared with a control group. To obtain better insights into the value of cardiac rehabilitation for inducing lifelong changes in physical activity habits, high-quality trials are required, with robust physical activity measurement and data analysis methods, to assess whether cardiac rehabilitation definitely leads to important improvements in physical activity behaviour. Furthermore, next to motivating patients who were used to a sedentary lifestyle to take up healthy physical activity habits, additional strategies might be needed in order to motivate patients who used to be active before surgery to go back to their earlier exercise habits taking into account their cardiac disease. This certainly is a challenge for healthcare providers following up patients after valve surgery, but a challenge worthwhile to be addressed since the benefits of a physically active lifestyle cannot be denied. 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. The opinions expressed in this article are not necessarily those of the Editors of the European Journal of Preventive Cardiology or of the European Society of Cardiology.