SAN FRANCISCO – Insulin use did not influence the higher risk for cardiovascular events after percutaneous coronary intervention compared with coronary artery bypass grafting in patients with diabetes and multivessel coronary disease, according to a secondary analysis of data from a 1,900-patient randomized trial.
The differences in clinical outcomes between coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI) with a drug-eluting stent were maintained regardless of the presence or absence of insulin treatment, Dr. George D. Dangas and his associates reported at the Transcatheter Cardiovascular Therapeutics annual meeting.
In the FREEDOM (Future Revascularization Evaluation in Patients with Diabetes Mellitus: Optimal Management of Multivessel Disease) trial, rates for the primary outcomes (a composite of death from any cause, nonfatal myocardial infarction, or nonfatal stroke) were significantly higher in patients treated with PCI than in those treated with CABG – 27% vs. 19% (N. Engl. J. Med. 2012;367:2375-84).
Dr. Michael E. Farkouh
The current analysis of data for the 1,850 patients who underwent revascularization compared the 32% who were on insulin at baseline with the 68% who were not on insulin treatment. Five-year rates for the primary endpoint were 29% in the insulin-treated group and 19% in the non–insulin-treated group, said Dr. Dangas, professor of medicine and surgery at the Icahn School of Medicine at Mount Sinai, New York.
Within both the insulin and noninsulin treatment subgroups, outcomes were worse with PCI than with CABG. In the insulin-treated subgroup, 5-year rates for the primary outcome were 32% after PCI and 24% after CABG. In the non–insulin-treated subgroup, 5-year rates for the primary outcome were 25% after PCI and 16% after CABG.
As in the main study, stroke rates were higher after CABG than with PCI in both the insulin and noninsulin groups, but rates of death, myocardial infarction, or major adverse cardiac and cerebrovascular events were higher after PCI compared with CABG. The fact that these trends appeared in both insulin and noninsulin subgroups is "something we really haven’t seen before so clearly," coinvestigator Dr. Michael E. Farkouh said at a separate press briefing
Baseline variables were very different in the insulin-treated and non–insulin-treated subgroups. "They were a sicker group of patients," said Dr. Farkouh, a cardiologist at the Icahn School of Medicine at Mount Sinai.
Patients on insulin were significantly more likely to be female and to have a higher body mass index; a longer history of diabetes; a higher hemoglobin A1c level; higher glucose level on the day of the procedure; higher blood urea nitrogen level; and a history of hypertension, peripheral neuropathy, congestive heart failure, and acute coronary syndrome. Insulin-treated patients were less likely to be New York Heart Association class 1.
The secondary analysis was limited because the study did not randomize patients based on insulin treatment, Dr. Dangas said at the meeting, which was cosponsored by the American College of Cardiology. The differences in outcomes between the insulin and noninsulin subgroups could be due to residual confounding, insulin resistance, or side effects of insulin treatment.
Not all patients in the FREEDOM trial have reached 5 years of follow-up. "We believe that there is no interaction" between insulin and outcomes "based on our statistical analysis, but we believe longer-term follow-up will help us to define this better," Dr. Farkouh said.
Approximately 26% of U.S. diabetes patients are treated with insulin.
FREEDOM was sponsored by the National Heart, Lung, and Blood Institute. Dr. Dangas reported having no financial disclosures. Dr. Farkouh reported financial associations with Eli Lilly, Sanofi, and other companies.
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