Chapter 3 - Why does AF matter?

Key points

  • Strokes in people with AF are more severe and have worse outcomes than strokes in people without AF
  • AF almost doubles the death rate from stroke
  • AF strokes are cardioembolic which leads the increased risk of more brain damage
  • AF increases disability from stroke
  • AF increases the risk of a stroke happening again

The burden of stroke for patients with AF is worse than just an increase in stroke risk. The strokes suffered by people with AF are also more severe,72 they are more frequently fatal4 55 and they are more likely to lead to disability,4 5 178 72 increased healthcare costs106 and extended hospital care than strokes in patients without AF.72 Moreover, AF-related strokes are more likely to happen again, adding not just to the risk of future strokes, but also to the potential for increased patient anxiety and a further reduction in quality of life.

Why does AF lead to more severe strokes?

The increased severity of strokes in patients with AF is thought to be related to the large size of the clots that ultimately block blood vessels in the brain. Almost all AF-related strokes are cardioembolic; which means that the clot forms in the chambers of the heart from where it travels downstream in the blood to the vessels of the brain. Clots will naturally grow rapidly in size as part of the body’s safety mechanism to prevent bleeding. The further a clot travels, the greater opportunity it has to increase in size. Once in the brain, a larger clot can block larger vessels. The bigger the vessel that is blocked, the greater the amount of brain tissue that is likely to be affected. And so it follows that the greater the amount of brain that has its blood supply cut off, the greater the chance of a severe stroke, death and disability.

AF causes half of all dangerous embolic strokes.52 Click to enlarge.

AF nearly doubles the death rate from stroke

Many aspects of strokes are more severe among AF patients but one of the most dramatic is mortality; the likelihood that a stroke will kill. AF-related strokes kill nearly twice as frequently as non-AF strokes. In a Danish clinical study, stroke patients with AF were 70% more likely to be killed than those without AF.72 A larger subsequent study of Italian stroke patients found that the increase in death rate among AF patients after 12 months was even higher; almost double the rate of those without AF.4 An Austrian stroke registry also demonstrated a near doubling of death rate from stroke in the presence, compared to the absence, of AF (25% versus 14%).55

12 months after a stroke nearly twice as many AF patients will have died compared to non-AF patients55

So powerful is this effect, AF has been found to be to be an independent predictor of death even after adjusting for age, sex and vascular risk factors.

A trend towards an increase in the overall early death rate in patients with AF over the last 20 years has also been reported,51 which may reflect the increasing age of the population. With both AF prevalence11 and AF death rate increasing, there is an urgent need to improve the management of AF, in particular to prevent the most common fatal consequences, such as stroke.

For a more thorough review of the long-term consequences and costs of AF-related strokes, please see chapter four.

Patients with AF are therefore a vital target population for reducing the overall burden of stroke on society.