To Bridge or Not to Bridge Anticoagulation, What Shall We Do?
Clinicians widely believe that anticoagulation bridging is needed, but scientific proof to indicate this practice is lacking. “Bridging in” typically means taking patients off warfarin or another anticoagulant prior to a surgery or procedure and substituting it with another form of anticoagulation, whereas “bridging out” refers to the postoperative period. “Full bridging” means the use of full intensity anticoagulation, such as intravenous (IV) unfractionated heparin, and “prophylactic bridging” indicates a low preventive dose of treatments such as low-molecular-weight heparin (LMWH).
Because of the complexity of standardizing terminology and bridging protocols for warfarin, LMWH, and other agents for various thromboembolic disorders, and with the recent introduction of newer thrombin and factor Xa inhibitors, bridging can create a number of miscommunications and logistical nightmares, and it’s hard to get everyone on the same page.
In fact, there are no randomized clinical trials that indicate bridging is the way to go. Without any scientific proof to indicate its need, one recent study1 reported bridging is unnecessary in the vast majority of patients, and that routine bridging may in fact do more harm than good. Researchers found that thromboembolism is uncommon in low- or intermediate-risk patients when warfarin is interrupted for 5 days or less. Frequent bleeding complications can result from bridging, and these can cause incisional pain, increase the length of hospital stays, and predispose patients to infections.
Whom Not to Bridge
At the American Heart Association (AHA) 2011 Scientific Sessions2 on November 13, 2011, Samuel Z. Goldhaber, MD, stated that patients undergoing dental cleaning and simple extractions,3 cataract surgery, or colonoscopy simply do not require bridging or interrupting their warfarin. Importantly, Dr. Goldhaber noted that the American College of Cardiology/AHA 2006 guidelines for the management of patients with valvular heart disease advise not bridging patients with mechanical aortic valves who have no other risk factors.4
Whom to Bridge
Dr. Goldhaber stated that patients who are “high risk” definitely should receive bridging. This includes patients with multiple prosthetic valves or “advanced” mitral valve disease and atrial fibrillation patients with a CHADS score of 3 or higher. In these individuals, it is important not to forget the option of IV unfractionated heparin given in the hospital. Because of its quick onset of action and short half-life, it can usually be discontinued a few hours prior to surgery. Post-surgery, unfractionated heparin can be restarted or LMWH given as desired.
Preoperative Aspirin Therapy Benefits Cardiac Surgery
A recent study5 reported that aspirin taken within 5 days of cardiac surgery is associated with a significant decrease for 30-day mortality, major adverse cardiocerebral events, postoperative renal failure, and average time spent in the intensive care unit when compared with nonaspirin therapy. Researchers reported the findings are significant because despite remarkable progress in cardiac surgery, the number of major complications remains high.
“Therapies targeted to prevent or reduce major complications associated with cardiac surgery have been few and ineffective so far,” said lead study author Jian Zhong, MD, of Thomas Jefferson University. “These complications are significant and costly both for the public health and the quality of patient life.”
The beneficial effects of preoperative aspirin use can be lifesaving for patients who have experienced heart attacks. Now this simple intervention can do the same for patients who undergo certain coronary surgeries. This outcome could lead to new preoperative treatment standards in cardiac medicine. PT
Mr. Brown is professor emeritus of clinical pharmacy and a clinical pharmacist at Purdue University College of Pharmacy, Nursing, and Health Sciences, Department of Pharmacy Practice, West Lafayette, Indiana. This column’s information is based on current studies and references, but it may be changed without notice with newer studies or with different patient populations.
1. Garcia DA, Regan S, Henault LE, et al. Risk of thromboembolism with short-term interruption of warfarin therapy. Arch Intern Med. 2008;168:63-69.
2. “Bridging” anticoagulation may not be necessary in vast majority of patients. TheHeart.org. www.theheart.org/article/1309811.do. Accessed December 1, 2011.
3. Jeske AH, Suchko GD. Lack of a scientific basis for routine discontinuation of oral anticoagulation therapy before dental treatment. J Am Dent Assoc. 2003;134(11):1492-1497.
4.Bonow RO, Carabello BA, Chatterjee K, et al. ACC/AHA 2006 guidelines for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation. 2006;114:e84-e231.
5. University of California - Davis Health System. Preoperative aspirin therapy can benefit cardiac surgery patients, study finds. ScienceDaily. www.sciencedaily.com/releases/2011/12/111205140605.htm. Published December 5, 2011. Accessed December 6, 2011.