Irregular Heartbeat

In atrial fibrillation, a malfunction of the pacemaker interrupts this sequence of contractions causing the atria to twitch erratically – known as fibrillation – and the ventricles to contract more often and irregularly.
Not surprisingly the heart works less effectively as a pump in atrial fibrillation, resulting in symptoms like a rapid heart rate, difficulty breathing, tiredness and light-headedness. Now there are also areas within the heart where blood flow is slow or stagnant. Where this happens blood clots can form and it is these that account for the increased risk of stroke associated with atrial fibrillation.

This means that the area of the brain beyond the clot can no longer receive the oxygen and nutrients that the blood normally delivers, causing the nerve cells to stop working and ultimately die.

This is what happens in a stroke – or more specifically in an ischaemic stroke (meaning one caused by an interruption in the blood supply). Because clots forming in the heart may be quite big they can block the larger blood vessels that supply large areas of the brain. Consequently, strokes arising from an irregular heartbeat or atrial fibrilation can be very serious, which is why it is so important to prevent clots forming in the heart.

Clots are formed in a process known as coagulation. This is a complex series of steps that must occur in a specific order. By interrupting one or more of these steps it is possible to reduce the likelihood of a clot forming and, thereby decrease the risk of stroke. Medicines that block the coagulation process in this way are known as anticoagulants.

For many years the most commonly used anticoagulants for stroke prevention in patients with atrial fibrillation have been the vitamin K antagonists. Medicines in this class, such as warfarin, are affected by interactions with a number of common foods and with other medicines. As a result, frequent blood tests are needed to find the appropriate dosage – a process known as monitoring.

Recent developments have resulted in new oral anticoagulants that can be used as alternatives to vitamin K antagonists. These new drugs are largely free from interactions and consequently do not require monitoring. Currently these include an oral direct thrombin inhibitor and an oral, direct Factor Xa inhibitor.

Ask your doctor what treatment is right for you