Anticoagulants: New vs Old?

Better the devil you know than the devil you don't.  One of the problems with progress is the risk of the unknown.  When it comes to long-term outpatient anticoagulation, warfarin, a vitamin K antagonist, has held court for eons.  However, because the level of anticoagulation can be affected by nutrition (vitamin K) and requires regular monitoring, we've worked on developing orals agents that did not have to deal with these issues and thus are easier to use.

Earlier this month, new oral anticoagulant, rivaroxaban (Xarelto), recently gained Food & Drug Administration approval for use in treating acute deep vein thrombosis and pulmonary embolism as well as recurrent conditions of the same.  However, because it is not a vitamin K antagonist, there is no practical means to reversing its effects should one begin to bleed.  

In a meta-analysis of randomized controlled trials also published earlier this month in the Archives of Internal Medicine, the authors concluded that use of anti-Xa or direct thrombin inhibitors is associated with an increase risk of bleeding after an acute coronary syndrome.  They reached their conclusion by reviewing 7 prospective RCTs involving 31,286 participants followed for at least 26 weeks on average, up to 124 weeks (or over 2 years).

Of course this is in direct contrast to the fanfare at last year's American Heart Association meeting when rivaroxaban was demonstrated to improve ACS outcomes.  How quickly 12 month's turns us on our head.  In the meantime, we need to have a thorough conversation with our patients about the pros & cons of their options, including the risk of bleeding events from vitamin K antagonists, Factor Xa inhibitors & direct thrombin inhibitors.  

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