McMaster University

McMaster University

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Health Sciences

Data released on groundbreaking trial on open-heart surgery

Published: March 26, 2012
André Lamy
Dr. André Lamy, an associate professor in the Michael G. DeGroote School of Medicine

The world’s largest randomized trial comparing heart bypass surgery done with a heart-lung machine (on-pump) and without it (off-pump) found that both techniques could be done safely. However, clinically relevant differences were revealed as well, according to data presented by researchers from the Population Health Research Institute of Hamilton Health Sciences and McMaster University. The results of the research are important because this news could introduce the concept of patient-specific decisions for bypass surgery.

The data will be presented today at the American College of Cardiology’s 61st Annual Scientific Session and the study will be simultaneously published in the New England Journal of Medicine.

"This introduces a new concept in cardiac surgery, allowing patient-specific decisions for bypass surgery," Dr. André Lamy, an associate professor in the Michael G. DeGroote School of Medicine said. "Off-pump procedures are trickier and more stressful, and the benefit is for the patient, not the surgeon, so in many places, they’re simply not done. My goal is to persuade surgeons to individualize the technique — to do off-pump bypass or on-pump when indicated — so their patients will benefit."

Heart disease continues to be a major cause of death in Canada and the world, and coronary artery bypass graft surgery (CABG) is a common treatment. CABG procedures consume more resources in cardiovascular medicine than any other procedure.

Currently, there are two different techniques used to perform heart bypass surgery: off-pump (operating on a beating heart) and on-pump (a heart lung machine is used to maintain blood circulation during surgery). Off-pump was developed in the last 10 to 15 years in an effort to decrease surgical complications typically related to on-pump surgery and associated with the heart-lung machine, which has been used since the 1960s.

The patient recovery benefits of the off-pump technique compared with the on-pump approach were previously unclear. It was previously believed the off-pump technique was a superior method, however, there was not enough evidence to support this theory.

Researchers at Canada’s top ranked research hospital conducted the CORONARY trial at 79 centres in 19 countries to compare the risks and benefits of off-pump and on-pump bypass to try to settle the issue. This Canadian Institutes of Health Research (CIHR) funded study was the largest international cardiac surgery study conducted to date.

Since October 2007, the CORONARY trial has enrolled 4,752 patients with coronary artery disease who were scheduled for CABG and randomly assigned to off-pump or on-pump surgery after a complete assessment to make sure they were suitable for both techniques.

For the primary composite outcome of death, heart attack, kidney failure, and stroke at 30 days post-bypass, the results were statistically neutral: 9.9 percent for off-pump patients and 10.3 percent for the on-pump group. Similarly, no differences were seen for individual events of the composite outcome. These results were a surprise. Based on previous meta-analyses, Dr. Lamy and his colleagues expected that off-pump CABG would decrease the rate of stroke and renal failure.

"This trial is important because more than a million CABGs are done every year around the world, and surgeons will now have the confidence that the two approaches are equally efficacious. However, long-term outcomes are also required to be confident of the durability of each procedure," said Dr. Salim Yusuf, Vice President of Research at Hamilton Health Sciences and Director of Population Health Research Institute at Hamilton Health Sciences and McMaster University.

The CORONARY trial will conduct safety and efficacy follow-up at five years and assess neuro-cognitive results at 30 days and at five years after CABG.

Study Article

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