The prevailing notion is that bypass surgery is superior to stenting in patients with diabetes. The truth, however, is more complicated, as the decision-makers learn to examine the individual pathologies in lieu of standardization. Often, this process is more art than science in taking into account all of the parameters of a patient’s disease.
In general, patients with diabetes are at a much higher risk for any kind of revascularization procedure because they have a lot of concomitant disease—both cardiovascular and extra-vascular. Whether undergoing stenting or bypass surgery, diabetic patients as a whole fare worse than nondiabetic patients.
Roxana Mehran, MD, director of outcomes research, data coordination and analysis at the Center for Interventional Vascular Therapy at New York-Presbyterian Hospital/Columbia University Medical Center in New York City, suggests that controlling glycemia might produce better outcomes in diabetic patients who are on both oral agents and insulin. She adds that insulin-dependent diabetics tend to fare worse in stenting than those taking oral agents, which may simply result from the severity of the disease in the insulin-dependent population.
David O. Williams, MD, chief of interventional cardiology at Rhode Island Hospital in Providence, however, suggests that specific lesion characteristics, more than insulin dependence, affect technical success of stenting diabetics. Williams concedes that some patients in this population should not be stented. “If it becomes a toss-up because of the patient’s anatomy, I would favor surgery. Clearly, there are diabetic patients with multivessel disease that can be treated appropriately with angioplasty—not all, but some,” he notes.
In the early 1990s, the NIH-funded BARI (Bypass Angioplasty Revascularization Investigation) trial was the first study to raise a concern about treating diabetics. The study found that diabetic patients with multivessel disease fared better with surgery than balloon angioplasty (see charts, above). At the time, bare-metal stents (BMS) and drug-eluting stents (DES) were not on the market.
Williams points out, however, that there was a patient subset in the BARI registry, who declined randomization, but had the same eligibility. The surgeon and patient decided the treatment. Two-thirds of the patients chose angioplasty and the results were comparable to those who chose surgery, according to Williams.
In the mid-1990s, Mehran and colleagues found that out of nearly 700 patients with multivessel disease, the diabetics did not do as well as the nondiabetics regarding stenting (BMS) versus coronary artery bypass graft (CABG) surgery (J Am Coll Cardiol 2004;43:1348-1355). Researchers from the JACC study also found that many insulin-dependent diabetics had more complications than those in the non-insulin-dependent group. “We know the vascular pathophysiology of atherosclerosis is a little different in patients with insulin-dependent diabetes. We find a lot more negative remodeling in them and their response to angioplasty might be very different from non-insulin-dependent diabetics. It’s very difficult to pinpoint why they are doing worse, but this patient population also has more diffused concomitant disease than non-insulin-dependent diabetic patients,” Mehran says.
Since then, the ARTS trial found no significant difference at five years in mortality and incidence of stroke or MI between stenting (BMS) and CABG in the study population of 1,200 patients with multivessel disease. Overall MACCE was higher in the stent group, driven by the increased need for repeat revascularization (J Am Coll Cardiol 2005; 46:575-81). A subset analysis of the 208 diabetic patients found a higher mortality rate in the stent group compared to the CABG group. Researchers also found that diabetics treated with stenting had a lower event-free survival at five years compared with non-diabetic patients, but the study was not powered to show mortality differences between diabetic and non-diabetic patients. Researchers suggested that differences in outcomes seen between BMS versus CABG for the treatment of multivessel disease are likely to narrow substantially with the advent of DES.
More recently, the HORIZONS AMI trial, which had a diabetic population of 16.5 percent—approximately 600 patients— and used DES, showed a benefit for diabetics who were on the anticoagulant bivalirudin