Cardiac rehabilitation (CR) plays a pivotal role in the contemporary management of myocardial infarction (MI) patients1 and several studies have documented the significant benefits on cardiovascular outcomes, both in terms of morbidity and mortality.2,3 CR has greatly evolved since its introduction and this has been reflected by the expanding indications for this holistic intervention.1,3 Exercise training exerts several physiological effects via both cardiac and extracardiac mechanisms,3,4 and has become one of the mainstays of CR programmes.3 Despite these positive data, certain patient subgroups tend to be referred to CR less often.3,5 Of these, patients not undergoing revascularisation present a particularly complex challenge given their suboptimal referral5 and higher risk status.6
A study by our group assessed the impact of a Phase II CR programme among MI survivors not undergoing revascularisation during hospitalisation, in terms of functional parameters assessed by cardiopulmonary exercise testing using a treadmill.7 A total of 349 patients from a single tertiary centre were included in this retrospective cohort study and the study population was mainly composed of male individuals (81.2%), with a mean age of 59.0±10.5 years. Of these, 12.6% had not been submitted to revascularisation during hospitalisation. Significant differences were present in terms of age, sex, history of coronary artery disease, prevalence of arterial hypertension, and smoking status. After the CR programme (mean number of sessions: 21.1±6.7), patients presented with significant improvements in cardiorespiratory fitness, as assessed by peak oxygen consumption (pVO2). Importantly, although patients not undergoing revascularisation during hospitalisation had a significantly lower pVO2 than the remaining patients (both at the beginning and at the end of the CR programme), there were no differences between these groups in terms of the benefit derived from the CR programme. This finding was maintained after adjusting for age and sex. Additionally, no differences were present between the groups in terms of the respiratory exchange ratio.
Previous data from patients with incomplete revascularisation have showed that a CR programme could be beneficial.8 In a study of 190 patients after an acute coronary syndrome (49 with incomplete revascularisation), a CR programme was well tolerated and presented significant increases in workload capacity, which did not differ between the study groups. Additionally, it should be noted that patients who did not undergo revascularisation tended to present with different risk profiles, namely in terms of a higher prevalence of comorbidities.6,9 As a result, the global scope of CR makes this intervention especially attractive for this subgroup of MI patients. The improvement in cardiorespiratory fitness (as assessed by pVO2) should also be highlighted since exercise capacity has been described as an important predictor of cardiovascular events in different groups of individuals.10
In conclusion, the results of the present study highlight the importance of CR programmes in MI survivors, namely in those who do not undergo revascularisation during hospitalisation. Future research should further explore this issue to fully ascertain the overall impact of CR on this higher-risk population, whose unmet needs in terms of secondary prevention still need to be improved.