SAN FRANCISCO, CA — An analysis of the FREEDOM trial, a study that showed a benefit of coronary artery bypass graft (CABG) surgery over PCI in diabetic patients with multivessel disease, confirmed that this benefit was maintained in patients who were treated with insulin.

For the insulin-dependent diabetic patients, the rate of major adverse cardiovascular events (MACE) was significantly higher than in patients not treated with insulin, but the advantage in terms of clinical outcomes with CABG over PCI was evident in both the insulin-dependent and non–insulin-dependent diabetic patients, report investigators.

Presenting the results of the FREEDOM subanalysis at TCT 2013 , Dr Michael Farkouh (Mount Sinai School of Medicine, New York) said that approximately one in four diabetic patients in the US are treated with insulin.

"Insulin is traditionally a marker of the duration of diabetes," said Farkouh, "so our interventional colleagues are often interested in these patients. For us on the medical side, we know that if we keep diabetics alive long enough, everyone will eventually require insulin. The issue is that insulin-treated diabetes is a marker of worse outcomes in PCI, and it's also a marker of high risk for wound infection in CABG patients."

Benefit in Both Subgroups

In FREEDOM, patients with diabetes and multivessel coronary artery disease treated with CABG surgery had significantly lower rates of death from any cause, nonfatal MI, or nonfatal stroke when compared with diabetic patients treated with PCI. In the trial, 602 patients were treated with insulin while 1248 did not receive the drug.

The insulin-treated patients had a higher body-mass index (BMI), a much a longer duration of diabetes (15.1 years vs 7.7 years), higher HbA1c levels, and more comorbidities than those not treated with insulin. Compared with those without insulin, the insulin-dependent diabetic patients had significantly higher rates of death, cardiovascular death, stroke, MI, and revascularization than those not treated with insulin. The 30-day and one-year MACE rates were also significantly higher.

Although the event rates were higher in the insulin-treated patients, the benefit of CABG over PCI was maintained, according to the FREEDOM investigators. At five years, the primary end point of death, MI, and stroke was 32% in the PCI arm and 24% in the CABG arm of insulin-treated patients, a statistically significant difference. The MACE rates were 25% in the PCI arm and 16% in the CABG arm among non–insulin-treated patients, also a significant difference.

"There were more strokes in the bypass patients but less MI and all-cause mortality in the PCI arm," said Farkouh.

Dr William O'Neill (Henry Ford Hospital, Detroit, MI) said that while he has always believed PCI should be abandoned in diabetic patients with multivessel disease, leaving this difficult-to-treat patient group to the surgeons, many of the diabetic patients with coronary artery disease are inoperable because they have diffuse disease.

"You have to asterisk all of this by saying 'in patients that are eligible for surgery,' " said O'Neill.

Farkouh agreed, but noted that the nature of diabetic arteriopathy has changed in the statin era, making the disease easier for surgeons to tackle with CABG. Surgeon Dr Pieter Kappetein (Thoraxcenter, Rotterdam, the Netherlands) agreed, saying that the number of diabetic patients ineligible for surgery because of the diffuseness of their coronary disease is very small.

Grant and research support for the FREEDOM trial was provided by Eli Lilly, Sanofi, Boston Scientific, and Cordis.

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