Optimal invasive strategy for multivessel coronary artery disease in elderly diabetic patients

We read with interest the study by Shah et al.¹ comparing treatment with coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI) for multivessel coronary artery disease (MVCAD) in elderly patients with diabetes mellitus (DM). Some additional points may be of interest.

Based on the results of the FREEDOM study², current guidelines on the management of stable coronary artery disease (CAD) from the European Society of Cardiology recommend CABG for the treatment of MVCAD in DM. Less evidence is available for the treatment of MVCAD in elderly patients. The same guidelines³ propose PCI in this group as the optimal strategy. In spite of this, the choice of the best treatment for MVCAD in both groups requires consideration of several variables and a multidisciplinary approach. The population which combines both risk factors (i.e. diabetes and older age) is an increasing clinical problem and there is sparse data on adequate management for these patients. Elderly patients are a growing population, more prone to develop complications after revascularization, more frequently diagnosed with chronic kidney disease and requiring a broad clinical evaluation before assigning them to any of the treatment options, including medical therapy. Special characteristics of CAD in DM, on the other hand, warrant anatomical and technical considerations, as CAD is likely to be diffuse and progressive, or involve left main disease. In light of these facts, the study by Shah et al.¹ assessing both invasive revascularization strategies from a real-life perspective enriches available data from randomized controlled trials (RCTs) and provides new evidence for the discussion of “borderline” patients.

The elderly are poorly represented in RCTs involving CAD. The reason might be higher risk, compared with younger patients, for complications after invasive procedures, including bleeding from the puncture site, contrast induced nephropathy and co-morbidities. However, the criterion for selection of the population as elderly with a cutoff of 65 years of age seems a rather low limit. This might influence interpretation of outcomes regarding the incidence of endpoints. Mean age of the population from RCTs vary around 65 years, which is not far from the cut-off in the discussed publication. There is, however, no firm definition of elderly age. Nevertheless, 65 years in the context of current prolonged life expectation may be a limitation.

PCI results in higher rates of repeat revascularizations than CABG in patients with MVCAD and DM in long-term follow-up⁴. In order to reduce the risk of restenosis, drug eluting stents (DESs) are recommended over bare metal stents (BMSs) for use in difficult patients populations including left main disease, MVCAD and DM^5,6. Among DESs, second-generation DESs may be more effective and have a safer profile in patients with DM⁷. Although the recommended type of stent for diabetics is DESs, the choice between DESs and BMSs in the elderly population is not as obvious. Similarly to diabetic patients, the elderly can share the benefits from DES implantation with reduced rate of repeat revascularization due to restenosis and subsequent hospitalization. At the same time, elderly patients are at a higher risk of bleeding during the long-term dual antiplatelet treatment required after implantation of DESs and more prone to have indications for anticoagulation, also the probability of non-cardiac surgical intervention shortly after stent placement is higher. In addition there is a higher probability of poor compliance with medical therapy^8–10. Shah et al.¹ do not clearly state what was the contribution of each type of stent (BMSs/first-generation DESs/second-generation DESs). Such information would influence the interpretation of outcomes as the stent type could influence the occurrence of endpoints, especially regarding repeat revascularization and myocardial infarction.

Regarding procedural characteristics, some additional information would be useful in the group treated with CABG. The pathophysiology behind the differences in outcomes of PCI and CABG in diabetic patients is rather complex. Some attribute better outcomes after CABG to the better durability of arterial bypass than coronary stents, manifested in lower rates of repeat revascularization¹¹. Others claim that complete revascularization with CABG is protective with regard to progressive atherosclerosis, vulnerable plaque and diffuse and complex anatomy in these patients. On the other hand, the invasive character of surgical procedure with extracorporeal circulation and manipulation of the aorta may increase the incidence of stroke after CABG⁴. Surprisingly, according to Shah et al.¹, the latter circumstance has no implication in the group of elderly diabetic patients, in whom stroke occurred with equal incidence in the PCI and CABG groups.

Available results from RCTs show that for patients with DM treated for MVCAD, there is no significant difference between CABG and PCI in terms of death and MI immediately after the procedure and in intermediate term follow-up⁴. CABG begins to be beneficial in longer observation, when it is associated with lower rates of death and MI than PCI⁴. Similar results are also documented in a real-world population of patients 65 years and older¹². Shah et al.¹ showed that, in the real-life cohort combining both elderly patients and diabetics, the tendency in favor of CABG over PCI starts to be visible as soon as after one year and is sustained in the longer term. The results direct attention towards cautious stratification of elderly patients and screening for DM, in order to identify a subpopulation of patients who could benefit more from CABG than commonly expected.

Transparency

Declaration of funding

This editorial was not funded.

Declaration of financial/other relationships

D.K. and B.M. have disclosed that they have no significant relationships with or financial interests in any commercial companies related to this study or article.

CMRO peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Acknowledgement

We wish to thank the team led by Ruchit M. Shah for giving us the raising this important clinical problem as well as all peer reviewers for efforts on enriching the value of the text.