June 2008 Press Release
THROMBOSIS GUIDELINES EMPHASIZE DIFFICULT CHOICES
FOR PREGNANT WOMEN
New Recommendations Address Presurgery and Pediatric Dilemmas
(NORTHBROOK, IL, June 24, 2008)—New evidence-based guidelines address the prevention and
management of thrombosis in key patient populations and reinforce recommendations related to the
routine use of preventive therapies. Published as a supplement in the June issue of CHEST, the peerreviewed
journal of the American College of Chest Physicians (ACCP), Antithrombotic and Thrombolytic
Therapy: ACCP Evidence-Based Clinical Practice Guidelines, Eighth Edition was developed by an
international panel of 90 experts and includes more than 700 of the most comprehensive
recommendations related to the prevention, treatment, and long-term management of thrombotic
disorders. The guidelines include chapters on the challenges in preventing and treating thrombosis in
pregnant women and children, and on managing peri- and postoperative patients, while also reinforcing
previous guidelines related to the routine use of preventive therapies, including aspirin.
“For years, clinicians have faced challenges in preventing and managing thrombosis in women
who are pregnant or patients who require surgery,” said guidelines panel chair Jack Hirsh, MD, FCCP,
Henderson Research Center, Hamilton, ON, Canada. “The new guidelines address many troublesome
issues in antithrombotic therapy and provide clinicians with a variety of options for care in special patient
groups.” Antithrombotic and thrombolytic therapies are used to prevent and treat thrombosis or blood
clotting that arises in arteries, veins, and the heart.
Pregnant Women
The new ACCP guidelines address challenging issues facing women who are pregnant or wish to
become pregnant while undergoing long-term antithrombotic therapy. Pregnant women taking vitamin K
antagonists (VKA), such as the anticoagulant warfarin, have an increased risk for birth defects and
miscarriage and are, therefore, advised to stop taking VKAs before 6 weeks of fetal gestation. However,
some pregnant women with certain types of mechanical heart valves may be continued on VKA therapy
because of concerns about the effectiveness of alternative anticoagulants in preventing stroke and valve
thrombosis. For other women taking VKAs who become pregnant, the guidelines recommend substituting
low-molecular-weight heparin (LMWH) or unfractionated heparin (UFH). The guidelines recommend
two options for doing this: (1) continuing VKA but performing frequent pregnancy tests to determine
when pregnancy has been achieved, followed by the substitution of LMWH or UFH as therapy; or (2)
substituting VKAs with LMWH or UFH prior to conception. Although the second option eliminates the
potential for fetal exposure to VKA, it provides additional challenges. LMWH and UFH are more
expensive than VKAs and must be administered through a once- or twice-daily injection as opposed to a
once daily oral dose of VKAs. In addition, long-term use of LMWH or UFH can be associated with
osteoporosis.
“If women substitute heparin prior to pregnancy and have difficulties conceiving, they may find
themselves taking the medication for a much longer timeframe than expected,” said guideline coauthor
Shannon Bates, MD, McMaster University and Henderson Research Centre, Hamilton, Ontario, Canada.
“This is not only inconvenient but also increases treatment costs and may be associated with long-term
risks for the mother.”
Children
Recommendations related to childhood stroke, one of the top ten causes of death in children, and
congenital heart disease have been substantially expanded since the previous guideline. Arterial ischemic
stroke (AIS), usually caused by embolism or thrombosis, is difficult to diagnose in children because
underlying health conditions are markedly different than those in adult stroke and up to 15% of children
with AIS have no apparent risk factors. The guidelines recommend that children with AIS receive initial
antithrombotic therapy until underlying causes can be determined, followed by maintenance therapy to
prevent long-term recurrence. In addition, the newly expanded guidelines on the prevention and treatment
of thrombosis related to congenital heart disease interventions include discussions of ventricular assist
devices and prosthetic heart valves.
“Care for children with major cardiac problems has improved dramatically. Many children who
previously died now survive, but thrombosis remains a major cause of secondary complications for these
children,” said Dr. Hirsh. “Effective antithrombotic therapy is critical if these children are to grow up as
normal, healthy children.”
Patients Undergoing Surgery
For the first time, the guidelines dedicate a full chapter to the perioperative management of
patients on long-term antithrombotic therapy who require surgery or other invasive procedures. Most
patients must temporarily stop receiving therapy just prior to undergoing surgery, as well as during
surgery, in order to minimize surgery-related bleeding. However, stopping antithrombotic therapy can
increase the risk of a thromboembolic event. To address this challenge, the guidelines recommend that the
risk of a thromboembolic event during interruption of therapy is balanced against the risk for bleeding
when antithrombotic therapy is discontinued just prior to surgery. The guidelines also recommend routine
use of thromboprophylaxis for patients undergoing major general, gynecologic, or orthopedic surgeries
and have been expanded to include bariatric and coronary artery bypass surgery.
General Recommendations
Overall, ACCP guidelines recommend thromboprophylaxis for most patients who are hospitalized;
however, they do not recommend routine use of thromboprophylaxis for patient groups with a very low
risk of venous thromboembolism. Low risk groups include patients undergoing laparoscopic surgery,
knee arthroscopy, or those who take long airplane flights. For these patients, physicians can make
decisions about thromboprophylaxis based on the individual patient’s thrombosis risk.
The guidelines
continue to recommend against the use of aspirin alone as a means to prevent venous thromboembolism
in any patient population because more effective methods are available.
The guidelines are endorsed by the American College of Clinical Pharmacy and the American
Society of Health-System Pharmacists. For a copy of the new guidelines, please visit
www.chestjournal.org.
ACCP represents 17,000 members who provide patient care in the areas of pulmonary, critical
care, and sleep medicine in the United States and throughout the world. The mission of the ACCP is to
promote the prevention and treatment of diseases of the chest through leadership, education, research, and
communication. For more information about the ACCP, please visit www.chestnet.org.
Contact:
Jennifer Stawarz, (847) 498-8306
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