Exercise outperforms PCI in stable coronary artery disease: habits versus evidence

Stable coronary artery disease, renamed “chronic coronary syndromes” (CCS) in the 2019 European Society of Cardiology (ESC) guidelines, remains one of the most frequent clinical scenarios in outpatient cardiology [1]. The process of coronary atherosclerosis can be modified by lifestyle adjustments, pharmacological therapies, and interventions such as percutaneous coronary intervention (PCI). The overwhelming success of PCI in reducing mortality in patients with acute coronary syndromes has led many to believe that PCI could also improve outcomes in CCS [2]. However, randomised clinical trials of PCI in CCS have shown that PCI does not reduce mortality, while it prevents spontaneous myocardial infarction rates at the expense of causing more periprocedural myocardial infarctions [2]. Therefore, guidelines recommend PCI only in selected patients with angina refractory to medical therapy [1]. Exercise-based cardiac rehabilitation (ExCR), on the other hand, has consistently demonstrated its effectiveness in improving survival and reducing hospitalisations in CCS [1,3]. Accordingly, ExCR is recommended as a class I, level of evidence A indication in the 2019 ESC Guidelines [1].
Unfortunately, CCS patients are referred far more frequently to PCI than to ExCR. Indeed, in the EuroCaReD registry, only 0-24% of patients were referred to ExCR without preceding PCI [4].

A randomised comparison of ExCR versus PCI for treatment of CCS does not seem feasible or ethical (as all patients should be offered ExCR). In the study by Buckley et al., the authors designed what could be called “the next best thing”. They compared ExCR and PCI, by analysing data from electronic medical records, in a propensity-score matched cohort of patients with CCS [5]. Thus, they gathered data on 18,383 patients, of which 67% received only PCI, 24% were only referred to ExCR, and 7% had both PCI and ExCR. In the matched cohort of 4,327 patients, ExCR was associated with significant reductions in all-cause mortality (relative risk reduction 63%), rehospitalisation (71%), myocardial infarction (28%), and stroke (42%) at 18 months compared to PCI alone. When comparing ExCR alone to ExCR + PCI, clinical outcomes were similar, except for new-onset heart failure which was less common in the ExCR + PCI group. The retrospective study design obviously has its limitations, including selection bias, under-reporting in medical records, and residual confounding. However, the large sample size, long-term follow-up, and important effect sizes consistent across different clinical outcomes are important assets of this study.

Using the power of “big data”, the authors performed an analysis that would not be possible in a randomised trial. This study thus reinforces the recommendations from the 2019 ESC Guidelines: all patients with CCS should be referred for ExCR, and PCI should only be performed in refractory cases.