Percutaneous Coronary Revascularization in Diabetic Patients with Multivessel Coronary Artery Disease: Importance and Feasibilit

Percutaneous coronary interventions (PCI) have been increasingly adopted for the treatment of coronary artery disease in patients with diabetes mellitus. This form of coronary revascularization is attractive because of its ability to avoid coronary artery bypass surgery (CABG), leading to shorter hospital stays and lower initial costs.¹ Nonetheless, the inability to completely revascularize patients remains the ‘Achilles Heel’ of percutaneous coronary interventions.¹ This limitation is much more apparent among patients with diabetes, who often have diffuse, severe, and progressive coronary artery disease with a higher frequency of more complex lesions.^2–6 Therefore, it is not surprising that among patients undergoing PCI, diabetic patients have significantly higher long-term morbidity and mortality than those without diabetes.^2,3 Improving the poor outcomes among diabetic patients undergoing PCI remains an important challenge for the interventional community. The article by Nikolsky et al.⁷ in this edition of the Journal of Invasive Cardiology investigates an important issue: Does complete myocardial revascularization improve outcomes after PCI in diabetic patients with multivessel disease? The authors evaluated 352 consecutive diabetic patients with multivessel coronary artery disease who underwent PCI at their institution. The majority underwent incomplete revascularization (73.3%), while the remaining patients had complete revascularization (26.7%). At a mean follow-up of 3.1 ± 1.7 years, overall major adverse clinical events (MACE = composite of cardiac death, Q-wave myocardial infarction, coronary artery bypass surgery, and repeat-PCI) were significantly higher in patients who were incompletely revascularized versus those with complete revascularization. They concluded that complete myocardial revascularization may improve the long-term prognosis after PCI of diabetic patients with multivessel coronary artery disease.

See Nikolsky, et al. on pages 102–106

However, significant limitations of this observational study exist, raising concerns regarding the validity of the conclusion drawn by the authors. The reasons for incomplete revascularization were cited as angioplasty of the culprit lesion only (43.4%), small vessel size (1.5-2.0%) of the non-intervened coronary artery (22.8%), moderate stenosis (18.6%), chronic total occlusion (6.6%), and other unspecified causes in the remaining patients. Since the majority of the revascularization procedures were repeat PCI (121/148) that were performed at the discretion of the physician, the inclusion of PCI as a component of MACE would bias the results in favor of the complete revascularization group at least for the patients in whom significant lesions were left unrevascularized (43.4%). Further, there is a lack of information regarding the differences between the two comparison groups with respect to the type of lesion, the size of the vessel intervened upon, and other vessel characteristics that influence immediate and long-term outcomes after PCI. Incompleteness of revascularization proposed by the authors is also quite ambiguous without proper quantification of the myocardium at jeopardy, as under-revascularized patients may vary in the amount of under-reperfused myocardium from minimal to extensive, influencing their future outcomes. Additionally, revascularization may not be important in an area of complete myocardial necrosis. It is likely that not only the differences in the characteristics mentioned above, but the higher risk profile of those incompletely revascularized (higher proportion of patients with prior myocardial infarction and left ventricular ejection fraction less than 40%), may have resulted in the observed differences in outcomes between the two groups. A randomized clinical trial of diabetic patients with multivessel disease who are angiographically amenable to complete percutaneous coronary revascularization and randomly assigned to receive complete or incomplete percutaneous revascularization strategies perhaps is the best way of addressing the study question. Observational data, such as in the current study, often have limited ability to address such a complex issue despite robust statistical methods. It is important to stress that complete myocardial revascularization is not feasible in a significant proportion of diabetic patients, more so with PCI than with CABG. Thus, inability to revascularize percutaneously is often a marker for more advanced or diffuse disease and for an adverse prognosis in diabetic patients. Surgical revascularization (for those in whom this is feasible) or incomplete percutaneous coronary revascularization with vigorous adoption of strategies of secondary prevention that include appropriate medical therapies (aspirin, beta-blockers, angiotensin converting enzyme inhibitors, aggressive lipid-lowering agents, tight glycemic and blood pressure control) and behavioral modification (smoking cessation, weight control, diet and exercise) would be the only options for management of coronary artery disease in this cohort. Furthermore, even in those diabetic patients with multivessel disease amenable to PCI or CABG, the latter appears not only to provide a more complete revascularization, but also results in better relief of angina, lower need for repeat revascularization procedures, and better long-term survival than PCI among diabetic patients.^8–10 It is possible that advances in interventional technology (newer stent designs, drug-eluting stents) as well as adjunctive therapies (platelet glycoprotein IIb/IIIa antagonists, thienopyridines) may likely tilt the equation in favor of percutaneous rather than surgical revascularization among diabetic patients amenable to both. However, this remains to be proven in future investigations. Finally, until such time as more data on the benefits versus the risks of complete/incomplete revascularization in diabetic subjects are available, the decision for complete or incomplete revascularization should be individualized and based upon the patient’s clinical condition, angiographic features (including the patient’s left ventricular ejection fraction) and noninvasive study data. Published national guidelines should be used to assist in this decision making process.