How to correctly assess the risk for thrombosis and risk for bleeding when starting or continuing antithrombotic treatment?
Mark Crowther, MD: Most of the time when antithrombotic therapy is being initiated, it is being initiated because of the presence of a life-threatening condition: atrial fibrillation with a risk of stroke or systemic embolization, acute deep vein thrombosis, or pulmonary embolism. What treating clinicians know pretty intuitively, I think, is that particularly acute deep vein thrombosis or pulmonary embolism are potentially fatal conditions. And so when you are starting a person on anticoagulants, it is very rare that you think that the risk of bleeding or other complications of the antithrombotic therapy exceeds the benefit.
Very rarely a patient might have a specific reason like active bleeding or an allergy like heparin-induced thrombocytopenia, which would affect your choice of anticoagulants, but for the vast majority of patients it is the thrombosis, not the acute bleeding, that is the decision-maker for initial therapy.
For most patients with acute deep vein thrombosis, you treat them the same way with low-molecular-weight heparin transition to warfarin or one of the newer agents.
For atrial fibrillation, again, either with warfarin or one of the other vitamin K antagonists or one of the newer agents there is relatively little risk modification or dose modification based on the patient’s initial presentation.