New Oral Anticoagulants: Now, a Practical Guide

New information is available nearly every week on the safe and effective use of the oral anticoagulants now approved as alternatives to vitamin K antagonists. The 3 available in the United States are the direct thrombin inhibitor dabigatran and the factor Xa inhibitors apixaban and rivaroxaban.
The benefits of the new oral anticoagulants (NOACs) over warfarin for the prevention of stroke in atrial fibrillation (AF) are attractive to physicians and patients alike and include fewer food and drug-drug interactions, an improved efficacy/safety ratio, and no need for regular monitoring. A key advantage, demonstrated in phase 3 clinical trials, is the lower rate of intracranial hemorrhage seen with all 3 drugs compared with warfarin.
 
In some circles the NOACs foment talk about a revolution in the management of stroke prevention in AF patients. In others, however, they provoke calls for judicious patient selection, heightened post-marketing surveillance, and strict adherence to the manufacturers’ prescribing information. 
  
There are a number of post-approval clinical loose ends that pose particular danger; the most notable is the lack of an antidote to the new drugs. Although the risk of intracranial hemorrhage has been shown to be reduced compared with warfarin, if it does occur, there is little that can be immediately done. Also, all 3 NOACs have relatively short half lives and so missing even one dose can greatly increase the risk of an embolic event. 

Pros, cons; revolution, restraint. And not a guideline in sight.
 
Enter the European Heart Rhythm Association’s Practical Guide on the Use of New Oral Anticoagulants in Patients with Non-valvularAtrial Fibrillation, published in the April 2013 issue of the European Heart Journal.  In the absence of current unified guidance for NOACs (not unusual given the drugs’ new class status) a EHRA writing group identified 15 topics covering concrete clinical scenarios and formulated the most practical answers possible based on available evidence. Topics range from start-up schemes to NOACs vs warfarin in patients with AF and malignancy. Specifically, the guide addresses:

1. Practical start-up and follow-up scheme for patients on NOACs
2. How to measure the anticoagulant effect of NOACs
3. Drug-drug interactions and pharmacokinetics of NOACs
4. Switching between anticoagulant regimens
5. Ensuring compliance of NOAC intake
6. How to deal with dosing errors
7. Patients with chronic kidney disease
8. What to do if there is a (suspected) overdose without bleeding, or a clotting test is indicating a risk of bleeding
9. Management of bleeding complications
10. Patients undergoing a planned surgical intervention or ablation
11. Patients undergoing an urgent surgical intervention
12. Patients with AF and coronary artery disease
13. Cardioversion in a NOAC-treated patient
14. Patients presenting with acute stroke while on NOACs
15. NOACs vs. vitamin K antagonists in AF patients with a malignancy

EHRA created a Web site that will offer the latest updated information. An excellent 10-point summary of the guide’s recommendations is available at the Cardiosource Clinical Community/Atrial Fibrillation Web page.

The American College of Cardiology (ACC) acknowledges the EHRA guide as an essential first step in answering the variety of questions being asked by all healthcare professionals who treat AF patients.  The ACC’s own Anticoagulation Initiative is well under way and will provide physicians and patients with tools to maximize NOAC use and safety. A recently launched ACC mobile app, the Anticoag Evaluator, helps calculate a patient’s stroke and bleeding risk and identify anticoagulant options.

Keep an eye on your regular professional alerts for new chapters in the unfolding NOAC story.