Assessing and reducing the risk of stroke

When AF or atrial flutter is diagnosed, the individual’s risk of stroke needs to be assessed in order to establish whether blood thinning treatment (anticoagulation) is needed. In people with heart valve disease, anticoagulation is usually needed. In those with structurally normal hearts, a simple risk scoring system is used, called the CHA2DS2-VASc score. This can be used to calculate the annual risk of stroke, and those who are under the age of 65 with no other risk factors (shown in the image) usually would not need any treatment, whereas those over the age of 65 or with risk factors stand to benefit from either warfarin or a newer drug (one of the Novel Oral Anticoagulants – or “NOACs”).

The NOACs (such as dabigatran, rivaroxaban, apixaban and edoxaban) do not require regular monitoring with blood tests, and have fared very well in head-to-head trials against warfarin, which have shown them to be at least as effective in reducing stroke compared to warfarin (reducing the risk by around two thirds from the baseline risk shown in the table) with a superior safety profile. However, they have a shorter safety track record and – at present – only for dabigatran is there a single drug which will rapidly and fully reverse the anticoagulant effect.

The decision as to whether to have warfarin or a NOAC (in those who stand to benefit from anticoagulation) is based on the individual’s preference.