The International Myeloma Working Group, a group of leading myeloma specialists, recently drafted guidelines for the prevention of blood clots in the veins in multiple myeloma patients. The group recommended the use of heparin or warfarin for patients with a high risk for developing blood clots and aspirin for standard-risk patients.

Dr. Antonio Palumbo of the University of Torino in Italy presented the draft guidelines at the International Myeloma Workshop (IMW) on May 6 in Paris. In email correspondence with The Myeloma Beacon, Dr. Palumbo said that a comprehensive set of guidelines should be available within the next six months.

Blood clots in the veins, or venous thromboembolism, affect over 1 percent of the general population per year and may cause soreness and reddening of the skin. Blood clots that occur in the deep veins within the body, a condition known as deep vein thrombosis (DVT), can be very serious. Patients with DVT may experience pain and swelling, and the condition may be life threatening if part of a clot becomes dislodged and blocks blood flow to vital organs.

Multiple myeloma patients experience a greater risk of developing blood clots because of the myeloma itself as well as myeloma-related treatments, in particular high-dose dexamethasone ^[1] (Decadron) and multi-agent chemotherapies. Previous studies have also shown a higher risk for blood clots among myeloma patients receiving either Revlimid ^[2] (lenalidomide) or thalidomide ^[3] (Thalomid) in combination with dexamethasone during the first few months of therapy.

Before administering treatment for the prevention (prophylaxis) of blood clots in the veins in a myeloma patient, the guidelines say the physician must identify the patient’s risk for developing blood clots. The guidelines identify patients at high risk of developing blood clots as those who have had heart disease, long periods of immobilization, major surgeries, or a history of blood clots. Standard-risk patients are those who have not experienced any of these risk factors.

For patients at high risk of developing blood clots, the guidelines recommend prevention with the anti-clotting drugs warfarin (Coumadin) or heparin for at least the first four to six months of myeloma therapy. Thereafter, high-risk patients may receive aspirin to reduce the risk of developing clots during later stages of treatment.

For myeloma patients with a standard risk of developing clots, the guidelines recommend 81 mg to 325 mg aspirin per day or other preventative measures at the physician’s discretion for at least the first four to six months of myeloma therapy.

Drawing on past studies, the guidelines indicate that the rate of blood clots in the veins decreased from 12.4 percent to 9 percent among myeloma patients receiving heparin as anti-clotting medication within the first six months of thalidomide-dexamethasone therapy. Moreover, the rate decreased from 12 percent to 2 percent among newly diagnosed myeloma patients receiving an anti-clotting medication during the first six months of treatment with Revlimid plus low-dose dexamethasone.

The guidelines suggest that patients who have completed a standard duration of anti-clotting therapy may discontinue prophylaxis if an ultrasound shows that blood flow in the veins has been restored. Moreover, patients may safely discontinue prophylaxis if they consistently show low levels of D-dimer, a protein fragment produced when a blood clot dissolves in the body, after three to six months of anti-clotting therapy.

A possible side effect of the anti-clotting drugs is bleeding caused by a decreased platelet count. The guidelines recommend constant monitoring of platelet levels during anti-clotting therapy.

For more information, please see the full guidelines ^[4] (pdf), which are available on the IMW website.