New Research Questions Need to Allow Blood-Thinning Medication to Clear From Patients’ Bodies Before They Undergo Heart Bypass Surgery

Contact: Amy Murphy,, 202-375-6476


(BETHESDA, MD) – Current guidelines from the American College of Cardiology and the American Heart Association recommend patients wait at least five days after receiving blood-thinning medication before undergoing heart bypass surgery. New research indicates these guidelines often are ignored – but suggests lower-risk patients may be better off as a result.

According to the research, published in the July 18, 2006, issue of the Journal of the American College of Cardiology, nearly nine out of 10 patients with unstable chest pain who received clopidogrel (Plavix®) treatment later underwent bypass surgery before the recommended five-day waiting period.

Although the surgery exposed the patients to increased bleeding risks, “these bleeding risks must be weighed against the benefits of clopidogrel use demonstrated in randomized clinical trials, as well as against the economic impact of delaying coronary artery bypass graft surgery,” the researchers state. The study was led by Rajendra H. Mehta, M.D., M.S., F.A.C.C., of Duke Clinical Research Institute and Duke University Medical Center in Durham, N.C.

Clopidogrel often is given to patients with chest pain or after heart attacks because it helps to prevent blood clots by interfering with the ability of platelets to stick together.

“I think we are trying to show that common sense practice of medicine is more prudent and does not lead to increased risk in patients, despite what guidelines suggest,” Dr. Mehta said. “So all decisions regarding coronary artery bypass graft surgery need to be made based on each patient’s clinical characteristics, the expertise and ease of the operating surgeon in managing such patients, when they give informed consent.”

This latest study looked at data on 2,858 patients with unstable angina who underwent heart bypass surgery at 264 hospitals participating in the CRUSADE (Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes with Early Implementation of the ACC/AHA Guidelines?) initiative. CRUSADE is a national quality-improvement program.

The researchers analyzed the outcomes of the 852 patients (30 percent of the total) who had received clopidogrel within 24 hours of being admitted to the hospital. Of these patients, 87 percent had their surgeries within five days. The patients had a significantly higher rate of blood transfusions (65.0 percent vs. 56.9 percent, for an absolute increase of 8.1 percent and an adjusted odds ratio [OR] of 1.36, 95 percent confidence interval [CI] 1.10 to 1.68). They also were more likely to need at least four units of blood (27.7 percent vs. 18.4 percent, OR 1.70, 95 percent CI 1.32 to 2.19). In contrast, acute clopidogrel therapy was not associated with higher bleeding risks if coronary artery bypass graft surgery was delayed more than five days (adjusted OR 1.18, 95 percent CI 0.54 to 2.58).

“Although bleeding risk is real when clopidogrel patients undergo early surgery within five days of drug treatment,” Dr. Mehta said, “the absolute increase in transfusion is not that high.”

He also noted that this observational study was not designed to answer questions about why most surgeons performed heart bypass surgery sooner than guidelines recommend.

“I can only speculate, as our study is unable to answer this question,” he said. “One, economic pressures dictate shorter hospital stays, and it is not practical and cost effective to wait for five days in-hospital before doing coronary artery bypass graft surgery. Thus, for stable patients, when we expect the coronary artery bypass graft surgery to go smoothly, we tend to take them to surgery early and not wait.

“On the other hand,” Dr. Mehta continued, “patients who are high-risk, we want them to minimize their high perioperative complications by providing to best baseline milieu before coronary artery bypass graft surgery for optimal outcomes. One of this happens to be waiting for more than five days to minimize the risk of perioperative bleeding, among other measures. Two, surgeons are getting better at managing clopidogrel-related bleeding after coronary artery bypass graft surgery and, therefore, have less resistance to operating on such patients.”

Sanjay Kaul, M.D., from Cedars-Sinai Medical Center in Los Angeles, Calif., who was not connected with this study, said the results offer real-world confirmation of the increased bleeding complications associated with clopidogrel that led to the guideline recommendation of a five-day waiting period before heart bypass surgery.

“In absence of definitive evidence in support of clopidogrel pretreatment, the potential risk for increased bleeding associated with coronary artery bypass graft surgery and the poor ability to predict surgical coronary artery disease, the prudent strategy is to withhold clopidogrel treatment until coronary anatomy is defined and the need for surgical revascularization is clarified,” Dr. Kaul said. “These data are consistent with the ACC/AHA guideline recommendations of stopping clopidogrel at least five days, and preferably seven days, to “wash off” the treatment effect prior to coronary artery bypass graft surgery.”

CRUSADE is a national quality improvement initiative of the Duke Clinical Research Institute. CRUSADE is funded by Millennium Pharmaceuticals, Inc. and Schering Corporation. The Bristol-Myers Squibb/Sanofi Pharmaceuticals Partnership (the makers of Plavix® brand clopidogrel) provides additional funding support.

Dr. Mehta receives speaker fees from Bristol-Myers Squibb.

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The American College of Cardiology is leading the way to optimal cardiovascular care and disease prevention. The College is a 34,000-member nonprofit medical society and bestows the credential Fellow of the American College of Cardiology upon physicians who meet its stringent qualifications. The College is a leader in the formulation of health policy, standards and guidelines, and is a staunch supporter of cardiovascular research. The ACC provides professional education and operates national registries for the measurement and improvement of quality care.

The American College of Cardiology (ACC) provides these news reports of clinical studies published in the Journal of the American College of Cardiology as a service to physicians, the media, the public and other interested parties. However, statements or opinions expressed in these reports reflect the view of the author(s) and do not represent official policy of the ACC unless stated so.

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