ACCP Updates Its Advice on Curbing Thrombosis Risks : Expanded VTE prophylaxis is a key topic.

▸ Pregnant women. Dr. Hirsh identified new guidelines for pregnancy as among “the most controversial and, I think, the most important” in the document.

Randomized trials are difficult to conduct in this population, so most of the recommendations receive a 2C grade that reflects weak evidence, noted Dr. Shannon M. Bates, who oversaw the chapter on pregnancy issues.

Nonetheless, “a great deal of work has gone into making sure that our recommendations are unbiased and clearly reflect the available data,” said Dr. Bates, director of the adult hematology residency training program at McMaster University Medical Centre in Hamilton, Ont.

“By distilling this information into clear recommendations that include a reflection of the quality of available data, we hope to make it easier for physicians to provide the best evidence-based care to their patients,” she added.

Key elements of the pregnancy guidelines include a recommendation against routine prophylaxis other than early mobilization in patients undergoing cesarean section; a recommendation against testing for inherited hypercoagulable states in women with a history of pregnancy complications; and deletion of a previous recommendation advocating antithrombotic therapy in women with pregnancy complications and a known inherited hypercoagulable state.

Guidelines were eased for patients who have inherited hypercoagulable states because the association of these conditions and pregnancy complications is backed by scant evidence, while screening and interventions are costly, might carry some degree of risk, and might provoke needless anxiety for women, Dr. Bates said.

The new guidelines also provide detailed recommendations for management of women with prosthetic heart valves who are considering pregnancy.

▸ Children. Greatly expanded guidelines “pretty well cover every conceivable thrombotic issue” in neonates and children, Dr. Hirsh noted.

Stroke is one of the 10 leading causes of death in childhood, but it is difficult to diagnose and predict based on risk factors. Therefore, the new guidelines recommend that any child with arterial ischemic stroke receive initial antithrombotic therapy until the underlying causes are understood, followed by maintenance therapy to prevent recurrence.

Detailed sections offer guidelines on the prevention of thrombotic events in children with congenital heart disease, including sections on ventricular assist devices and prosthetic heart valves.

▸ Treatment of DVT. The guidelines offer two options—one monitored and one unmonitored—for subcutaneous heparin administration for acute DVT, Dr. Merli said in an interview.

The first regimen calls for an initial dose of 17,500 U or a weight-adjusted dose of about 250 U/kg every 12 hours, with the dose adjusted to achieve and maintain an activated partial thromboplastin time (aPTT) prolongation that corresponds to plasma heparin levels of 0.3–0.7 IU/mL anti-Xa activity when measured 6 hours after injection (rather than beginning therapy with the smaller initial dose).

The second option is a fixed-dose, unmonitored regimen that calls for an initial dose of 333 U/kg followed by a twice-daily dose of 250 U/kg.

“It's good to have choices,” Dr. Merli said.

The guidelines also suggest for the first time the use of catheter-directed thrombolysis with thrombus fragmentation and/or aspiration in “selected patients with extensive acute proximal DVT who have a low risk of bleeding,” but advocate this pharmacomechanical approach only if “appropriate expertise and resources are available.”

The guidelines also acknowledge the feasibility of reducing international normalized ratio monitoring during anticoagulation therapy in very low risk patients with an unprovoked DVT who have been intensively monitored for 3 months following standard protocols, Dr. Merli noted.

'It's good to have choices' for treatment of acute DVT. DR. MERLI