‘Cardiac rehabilitation works’: but it should be tailored individually, started early, and followed for a lifetime

Abstract

Regular exercise and cardiovascular lifestyle adaption have become a major issue in cardiovascular treatment in a primary as well as in a secondary preventive setting. Still, in secondary prevention, evidence has mainly been gained from meta-analyses, where relevant clinical endpoints, such as cardiovascular mortality and overall mortality, as well as recurrent cardiovascular events and hospitalizations were shown to be significantly lower in patients following cardiac rehabilitation after a cardiovascular event. As such, cardiac rehabilitation can no longer be seen as a possible addition to standard (e.g. pharmacological) therapies—it has to be established as the crucial fundamentum in multimodal cardiovascular treatment. In primary prevention, a substudy of the PURE trial recently demonstrated that regular exercise is able to reduce cardiovascular events in individuals that follow a regular training independently from further cardiovascular risk factors. Moreover, these benefits follow a ‘dose–effect relationship’, particularly regarding exercise (‘the more the better’). On the other hand, more than a decade ago, the ‘INTERHEART’ study group outlined the importance of multimodal lifestyle changes as it is the combination of risk factor reduction that strikingly decreases cardiovascular risk. In this issue of the European Heart Journal, Doimo and colleagues provide a relatively large study to evaluate the long-term clinical impact of cardiac rehabilitation which adds important evidence to the issue and holds some important messages for our daily clinical practice. Firstly, cardiac rehabilitation works. Confirming many other studies in smaller cohorts with a relatively short follow-up and, sometimes, with only surrogate endpoints, this study demonstrates that participation in cardiac rehabilitation after ST-segment elevation myocardial infarction (STEMI), non-ST-segment elevation myocardial infarction (NSTEMI), coronary artery bypass graft (CABG), or planned percutaneous coronary intervention (PCI) was independently associated with a reduction of the composite endpoint of hospitalizations for cardiovascular causes and cardiovascular mortality. This combined endpoint was mainly driven by the reduction of hospitalizations; however, this is a crucial single clinical endpoint for patients suffering from chronic cardiovascular disease. The fact that this study could not adequately confirm the results of a recent Cochrane analysis, showing a reduction in pooled cardiovascular mortality and hospital admission with exercise-based cardiac rehabilitation, is hardly surprising: some confounders are difficult to measure and were not assessed in this study (e.g. adherence to pharmacological therapy). Furthermore, we should be aware of the fact that most of the existing data on cardiac rehabilitation, which have been used for meta-analyses, are quite outdated as pharmacological and particularly interventional therapy has massively improved within the last years. However, once more, this highlights the need for current prospective trials in this field. Nevertheless, the combined endpoint for hospitalizations for cardiovascular causes and cardiovascular mortality was strikingly positive and the authors provided an additional propensity score analysis, as a feasible way to specify their results, and could even show a significant reduction of cardiovascular and total mortality in the cardiac rehabilitation group. However, one of the major limitations of this statistical method is, again, that it only accounts for observable covariates. Latent variables, that are obviously present in the setting of secondary cardiovascular prevention, still remain even after matching. Furthermore, although the study sample is quite large compared with existing studies, it might still be low for propensity score matching. A second important message of this trial is the fact that cardiac rehabilitation has to be implemented early after an event. Existing data have clearly demonstrated that a delay in starting cardiac rehabilitation may have a fatal impact on participation and adherence to such a programme. As an example, every day of delay between hospital