CABG Guidelines Get New Update

Hormone replacement out, aspirin in, as cardiology experts change the rules for coronary artery bypass graft surgery

(Bethesda, MD) The American College of Cardiology (ACC) and the American Heart Association (AHA) have issued a revised set of guidelines for the management of patients undergoing coronary artery bypass grafting. In contrast to the previous guidelines published in 1999, the new update says no to hormone replacement therapy and yes to aspirin for patients undergoing this common surgical procedure.

The new guidelines also stress the importance of statin and beta blocker therapy in all post-CABG patients, as well as anticoagulation with warfarin in patients who develop sustained abnormal heart rhythms after bypass. The document is published on the Web sites of the American College of Cardiology at http://www.acc.org/clinical/guidelines/cabg/index.pdf and the American Heart Association www.americanheart.org and will appear in the September 1 issue of the Journal of the American College of Cardiology and the August 31 issue of the Circulation: Journal of the American Heart Association.

We've significantly updated a number of sections of the 1999 guidelines to incorporate the most recent evidence from randomized trials. One important example is in the area of hormone replacement. Until the randomized trials were published, we were generally recommending the initiation of hormone therapy in women after their bypass, but in this document, it is not recommended at all, said Dr. Kim Eagle, co-chair of the guidelines writing committee.

The updated guidelines continue to emphasize quality of life as well as quantity. The guidelines now recognize that CABG is very effective for the relief of symptoms, even when it may not prolong life, said Dr. Robert A. Guyton, co-chair of the writing committee. This is an important evolution for us. In the 1990s, when guidelines for CABG were first issued, we focused more on quantity, but now we are interested in the quality of life, as well as length of life, he said.

An important aim of the revised guidelines is to optimize the medical management of bypass surgery patients, Dr. Eagle said. They really focus on treating atherosclerosis after CABG. For example, in the past, many patients were told to discontinue aspirin for some time prior to their surgery to reduce bleeding risk, but now we know that staying on aspirin is good for patients because it reduces the likelihood that their grafts will clot, he said.

Another area that has been significantly updated is the section comparing multivessel angioplasty and stenting with bypass surgery. Recent evidence from randomized trials now suggests that either option is reasonable, with five-year outcomes of both techniques showing similar results.

It's fair to say that the era of coronary stenting has improved, or reduced the need for repeat vascularization in patients who need stents. At the same time, the broader use of the left internal mammary artery has improved the benefit of coronary bypass surgery. So, on the one hand, angioplasty has a lower upfront risk, but on the other hand, there is a larger likelihood that patients who get angioplasty will require subsequent interventions. So, for patients who are eligible for both therapies, a lot of the final decision comes down to their own personal preference, he said.

However, the jury is still out as to the relative benefit of off-pump CABG. Although the results of several small studies appear to show fewer neurologic complications with off-pump bypass, the guidelines committee did not feel that their evidence was compelling enough to make a specific recommendation in favor of the newer technique.

One of the big questions many patients have had is whether the risk of stroke or other neurologic complications is lower with off-pump bypass surgery. But so far, the answer to that question is not absolutely clear. If you actually look at randomized clinical trials that have taken eligible patients for either methodology, the amount of difference in length of stay or neurologic complications has not been dramatic and we still have yet to prove to ourselves that off-pump bypass is dramatically better than on-pump bypass. We're certainly in no position right now to say that every patient who has bypass surgery should have it off-pump, Dr. Eagle said.

Source: The American College of Cardiology, press release, August 5, 2004

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Last Editorial Review: 9/3/2004