Stroke prevention with appropriate thromboprophylaxis still remains central to the management of atrial fibrillation (AF). Thus, a crucial part of AF management requires the appropriate use of thromboprophylaxis. The European Society of Cardiology Guidelines de-emphasise the ‘artificial’ low, moderate and high risk categorisation and recommends a risk factor based approach with the ‘CHA2DS2-VASc’ score. Bleeding risk is also recommended using the HAS-BLED score, which has been well validated, and outperforms other risk scores.
A high HAS-BLED score (≥3) is indicative of the need for regular review and followup, but should not be used as a reason for stopping oral anticoagulation. The patients with a high HAS-BLED score derive a higher net clinical benefit when balancing ischaemic stroke and intracranial bleeding.
The ESC Guidelines for AF recommend that OACs should be delivered whether as one of the novel OACs, or well controlled adjusted dose VKA. One issue to how best to identify the
patients who would do well on VKAs, with good quality INR control and high percentage time in therapeutic range. A new score (SAMe-TT2R2) recently described score can predict those who would do well on Vitamin K antagonists (SAMe-TT2R2 score 0-1) or those who are likely to have poor anticoagulation control with VKA (SAMe-TT2R2 score ≥2) where a NOAC could be a better option [see Table].
When adjusted dose Vitamin K Antagonist (eg Warfarin) cannot be used where an OAC is recommended, due to difficulties in keeping within therapeutic anticoagulation, experiencing side effects or inability to attend to undertake INR monitoring, one of the NOACs is recommended (Class I recommendation). Secondly, where an OAC is recommended, one of the NOACs—either a direct thrombin inhibitor (Dabigatran) or an oral factor Xa inhibitor (e.g. Rivaroxaban, Apixaban)—should be considered instead of adjusted-dose Vitamin K Antagonists (VKA, eg. Warfarin, INR 2 – 3) for most patients with AF (Class IIa recommended).
The 2012 guidelines provide specific recommendations for the NOACs that were licensed when the Guidelines were written, namely for Dabigatran and Rivaroxaban. Dabigatran is also specifically mentioned in the recommendation for peri-cardioversion anticoagulation management. Since the publication of the 2012 Guidelines, another NOAC, Apixaban has been licenced, and any guideline updates would need to incorporate recommendations pertaining to this drug. Also, more data are emerging for subgroups and ancillary analyses from the large Phase 3 trials that would inform recommendations on specific subsets of patients with AF.
Whilst the 2012 Guidelines provided some text on special situations, no specific recommendations were made given the limited data at the time of writing – however, future updates should rectify this.
In May 2013, EHRA also published a practical guide on the use of NOACs in AF, with comprehensive guidance on how to manage typical scenarios in patients taking these drugs
, for example, in those presenting with an ischaemic stroke, acute coronary syndrome, bleeding, operative procedures etc.