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Bypass surgery better for diabetics than angioplasty, study finds

Peter Munk Cardiac Centre cardiovascular surgeons perform coronary artery bypass surgery (photos by Nicole Bodnar)

An international clinical research trial has shown that patients with diabetes whose heart disease is treated with bypass surgery live longer and are less likely to suffer severe complications than those who undergo angioplasty.

“We’ve shown that bypass surgery saves one extra life for every 20 patients with diabetes who are treated for multi-vessel coronary artery disease,” said lead author, Michael Farkouh, associate professor of medicine at the University of Toronto and Chair of the Peter Munk Centre of Excellence in Multinational Clinical Trials, University Health Network (UHN).

Published online Nov. 7 in The New England Journal of Medicine, the study was co-led by researchers from New York’s Mount Sinai Hospital.

Five years after treatment, patients who received coronary artery bypass grafts had lower combined rates of strokes, heart attacks, and deaths (18.7 percent) than those who underwent angioplasty (26.6 percent).

Strokes were slightly more common among the bypass group than in the angioplasty group; however, more angioplasty patients died from any cause (16.3 percent) than CABG patients (10.9 percent).

“Based on these results, we believe that coronary artery bypass surgery should be standard therapy for the millions of patients worldwide with diabetes who have more than one diseased vessel,” said Farkouh.

Coronary artery disease - the build up of plaque in the coronary arterie - is the most common form of heart disease and can lead to chest pain, heart failure and heart attack. The study focused on diabetes because patients with diabetes have cardiac events more often than patients who do not have diabetes, and require more follow-up care than other patients.

According to the Public Health Agency of Canada, almost 2.4 million Canadians live with diabetes.

“This study will challenge the prevailing ambiguity between bypass surgery and angioplasty for multi-vessel coronary artery disease,” says Farkouh. “Bypass surgery saves lives and reduces the chance of complications in a high-risk group of patients with diabetes.”

Cardiovascular disease is a major complication of diabetes and the leading cause of early death among people with this disease — about 65 percent of people with diabetes die from heart disease and stroke. Adults with diabetes are two to four times more likely to have heart disease or suffer a stroke than people without diabetes.

“The benefits of bypass surgery are so significant that they’re what you’d expect to see between a patient who is and a patient who isn’t taking medication to control cholesterol,” says Farkouh.

A total of 1,900 patients were enrolled at 140 international centers during the trial, which began in 2005 and ended in 2010. All participants had diabetes and more than one diseased artery, and 83% had disease in three vessels. Half the participants received bypass surgery and the other group received angioplasty – which includes using a balloon or other device to clear blockages from arteries, as well as implanting drug-releasing stents.

The study followed patients for a median of four years and a minimum of two. Patients in both streams of the study were prescribed optimal medical management for control of high LDL cholesterol, high blood sugar levels and high blood pressure. The result assessed all-cause mortality, non-fatal heart attacks, and non-fatal stroke.

The research was supported by grants from the National Heart, Lung, and Blood Institute with provision of stents from Cordis, Johnson and Johnson and Boston Scientific, provision of abciximab and an unrestricted research grant from Eli Lilly and provision of clopidogrel from Sanofi-Aventis and Bristol Myers Squibb.

Farkouh’s research is also supported by Toronto General and Western Hospital Foundation’s Peter Munk Cardiac Centre campaign.