Diabetes and coronary revascularization

Patients with diabetes mellitus account for approximately 25% of the nearly 1.5 million coronary revascularization procedures performed each year in the United States and experience worse outcomes compared with nondiabetic patients.

To summarize the current state of evidence comparing the effectiveness and safety of coronary artery bypass graft (CABG) surgery and percutaneous coronary intervention (PCI) in diabetic patients and to examine developments that may affect future outcomes in this high-risk group.

Using the key terms diabetes mellitus, revascularization, coronary artery bypass, angioplasty, and coronary intervention, we searched MEDLINE from 1985 to 2004 for all randomized controlled trials (RCTs) comparing CABG surgery and PCI that reported outcomes in diabetic patients. Bibliographies and the Web sites of cardiology conferences were also reviewed. Studies comparing drug-eluting stents and bare-metal stents were identified in a similar fashion. The literature was reviewed to identify clinical measures that may impact revascularization outcomes in diabetic patients.

We identified 6 RCTs comparing CABG surgery and PCI in a total of 950 diabetic patients. A mortality benefit for CABG over balloon-only PCI has been demonstrated in diabetic patients with multivessel coronary artery disease but has not been clearly established against stent-assisted PCI or in high-risk CABG patients. Use of glycoprotein IIb/IIIa receptor inhibitors has improved survival in diabetic patients undergoing PCI. Restenosis after PCI in diabetic patients has led to substantially higher repeat revascularization rates than after CABG. The use of drug-eluting stents has led to dramatic reductions in restenosis in diabetic patients. Ongoing RCTs comparing CABG and PCI using drug-eluting stents in diabetic patients will clarify the impact of these advances on outcomes.

There is a relative lack of data from RCTs specifically comparing CABG surgery and PCI as currently practiced in diabetic patients. The mortality advantage and decreased rates of revascularization seen with CABG in subgroups from early trials may not be applicable in the era of drug-eluting stents, glycoprotein IIb/IIIa inhibitors, and the latest medical therapies.