NEW YORK -- June 24, 2008 -- New guidelines from the American College of Chest Physicians (ACCP), published as a supplement in the June issue of CHEST, address the prevention and management of thrombosis in key patient populations and reinforce recommendations related to the routine use of preventive therapies.
The evidence-based clinical practice guidelines were developed by an international panel of 90 experts and include 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, 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 panel chair Jack Hirsh, MD, Henderson Research Center, Hamilton, Ontario. "The new guidelines address many troublesome issues in antithrombotic therapy and provide clinicians with a variety of options for care in special patient groups."
Guidelines for 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 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 2 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.
Guidelines for Children
Recommendations related to childhood stroke and congenital heart disease have been substantially expanded since the previous guideline. Arterial ischaemic 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.
Guidelines for 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 minimise 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, gynaecologic, or orthopaedic surgeries and have been expanded to include bariatric and coronary artery bypass surgery.
General Recommendations
Overall, the ACCP guidelines recommend thromboprophylaxis for most patients who are hospitalised. However, they do not recommend routine use of thromboprophylaxis for patient groups with a very low risk of venous thromboembolism. 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.
SOURCE: American College of Chest Physicians
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