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Expert reviews revascularization strategies for CAD in diabetes

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WASHINGTON — CABG remains a superior strategy for revascularization in patients with diabetes and CAD, but other approaches should not be discounted, a speaker said at the American College of Cardiology Scientific Session.

CAD in patients with diabetes is complex and, therefore, difficult to treat, according to Konstantinos Dean Boudoulas, MD, associate professor of medicine, section head of interventional cardiology and director of the cardiac catheterization laboratory at The Ohio State University.

Moreover, in patients with diabetes, multiple factors may complicate treatment, including comorbidities, such as chronic kidney disease, or therapy with insulin, which has been associated with an increase in MACE. Consequently, selecting the best treatment strategy for these patients requires careful consideration of the data.

Available evidence

Patients with diabetes tend to have worse survival than those without diabetes regardless of the procedure, Boudoulas said, but according to data from the BARI trial, 10-year survival was significantly better among patients with diabetes who underwent CABG, as compared with angioplasty.

“Interestingly, if you break down the modality of revascularization — whether patients received an internal mammary artery or vein grafts during surgery or angioplasty — there was no significant difference in survival at 10 years between diabetic patients who received vein grafts and those who underwent [angioplasty]. However, patients who received an internal mammary artery to a left anterior descending artery had increased survival at 10 years, showing the superiority of left internal mammary artery to left anterior descending in the diabetic patient,” Boudoulas said.

The FREEDOM trial, which evaluated PCI vs. CABG in patients with diabetes and multivessel disease, offers more contemporary data, he said. Similar to results from the BARI trial, patients who underwent CABG fared better compared with those who underwent PCI. The lower MACE rates observed in the CABG group were primarily driven by a decrease in MI and all-cause mortality, although patients in the CABG group had an increased risk for stroke.

Boudoulas said a subgroup analysis of the FREEDOM trial that evaluated left anterior descending artery involvement yielded another interesting finding consistent with data from the BARI trial. If patients lacked left anterior descending artery involvement, rates of death, MI or stroke at 5 years were similar between treatment groups. However, in patients with left anterior descending artery involvement, essentially all received a left internal mammary artery to the left anterior descending artery and had a decreased rate of events with CABG vs. PCI.

“This benefit likely occurs because a left internal mammary artery to the left anterior descending is a superior form of revascularization in terms of patency,” he said. “Also, patients with diabetes have diffuse disease, so you can bypass most of these lesions.”

Although FREEDOM and BARI provided important insights regarding the use of CABG vs. PCI, the data are older and the drug-eluting stents used were first generation, according to Boudoulas.

Even so, results from more recent studies using second-generation DES also favor CABG over PCI in patients with diabetes, he said. For instance, in the BEST trial, the rate of a composite of death, MI or target vessel revascularization was reduced in patients who underwent CABG vs. PCI among those with diabetes; however, a difference was not seen in those without diabetes. The study had relatively short follow-up of 2 years, Boudoulas said.

Approaches to revascularization

When determining the optimal revascularization strategy for patients with diabetes, physicians should bear several factors in mind, such as complexity of CAD, according to Boudoulas.

Research from the BARI 2D trial shows that in patients with diabetes and low SYNTAX scores, MACE rates at 5 years were similar between those who received medical therapy and those who underwent revascularization with PCI or CABG, he said. Patients with intermediate or high SYNTAX scores, however, experienced a decrease in MACE rates with CABG compared with PCI at 3 years. Patients with diabetes assigned medical therapy also generally needed revascularization at 5-year follow-up.

Mortality also appears to be lower with CABG, according to Boudoulas, who cited a meta-analysis showing that CABG, compared with PCI with BMS or DES, decreased mortality at 5 years in patients with diabetes.

When comparing PCI treatment modalities, study results indicate that DES yields better outcomes compared with BMS, and second-generation DES may be superior to first-generation DES in patients with diabetes, Boudoulas noted.

Currently, information on the use of bioresorbable vascular scaffolds in patients with diabetes is limited, but 1-year data show comparable rates of target vessel failure between patients with diabetes and those without diabetes. Rates of TVF with the BVS were also comparable to those seen with a second-generation DES at 1 year in patients with diabetes.

The hybrid approach

Since left internal mammary artery to the left anterior descending artery appears to be the superior revascularization strategy for most patients with diabetes, the hybrid approach can be considered, Boudoulas said.

In a study comparing the hybrid approach, which involved left internal mammary artery to the left anterior descending artery and PCI to the non-left anterior descending vessels, with standard CABG and multivessel PCI, 3-year follow-up showed that the rate of a composite of death, MI, stroke or repeat revascularization was significantly lower in the hybrid approach group vs. the CABG and PCI groups.

The hybrid approach offers several advantages, according to Boudoulas. For example, the procedure is less invasive than standard CABG with the potential to utilize a minimal invasive access and off-pump.

“The hybrid approach utilizes the [left internal mammary artery] to the left anterior descending artery, which has most of the survival benefit,” he said. “It decreases coronary pulmonary bypass, if that’s used at all, and surgical times. It also avoids clamping the aorta.”

Boudoulas also said the hybrid approach allows substitution of stents for grafts, which provide a good form of revascularization, as well as fostering close collaboration between the interventional cardiologist and cardiothoracic surgeon.

“The major key advantage to the hybrid operating room is that a left internal mammary artery angiogram can be performed immediately after surgery, prior to closing the chest, with the ability to revise any defect before the patient even leaves the operating room,” he said. – by Melissa Foster

Reference:

Boudoulas KD. Core curriculum: Revascularization in special populations. Presented at: American College of Cardiology Scientific Session; March 17-19, 2017; Washington, D.C.

Disclosure: Boudoulas reports consulting for GE Healthcare.