Stroke Risks from Afib
A stroke happens when an artery that carries blood to the brain gets clogged by a blood clot (ischemic stroke) or ruptures (hemorrhagic stroke), depriving the brain of oxygen. Without oxygen, the nerve cells in the brain die, and cannot be restored. This causes permanent disability in the parts of the body controlled by the impacted nerve cells.
Ischemic strokes are the most common strokes as about 70–80 percent of strokes are due to blood clots. These clots can either form in the arteries going to the brain, or can come from some other part of the body. Most of the clots that come from other parts of the body are formed during atrial fibrillation. 1
One of the two types of ischemic strokes is called a Transient Ischemic Attack (TIA). They are often called "mini-strokes", and are considered to be warning strokes as a blood clot temporarily blocks an artery. TIAs usually last no more than five minutes, and may only last for seconds. They leave no permanent damage.
If you've had a TIA, you are much more likely to have a stroke. One-third of those who have had a TIA will have a stroke, often within a year. If you have a TIA, get emergency medical attention immediately.
When you have a full-fledged stroke, the nerve cells that control the functions of the body are generally damaged so that stroke survivors lose many body functions, such as motor skills, muscle movement, speech, vision, hearing, senses, memory, thinking, and problem-solving.
Stroke survivors often suffer paralysis or difficulty feeling and moving on one side of the body as well as impaired vision on one side. Speech may be slurred or distorted, and some survivors may have difficulty in thinking clearly.
Rehabilitation may be helpful in regaining some of the lost skills or finding a work-around for those that cannot be restored.
Stroke and Atrial Fibrillation
When the heart is overworked, weakened, and enlarged, it works even harder, which leaves more blood pooled in the atria. The atria quiver during atrial fibrillation, and thus don't completely empty, allowing blood clots to form in the atria.
If a clot breaks loose, it can be carried to the small arteries feeding the brain, blocking the arteries and cutting off oxygenated blood to the nerve cells in the brain, causing a stroke. The longer the artery is blocked, the more nerve cells will die, and they cannot be rejuvenated.
The table shown provides some interesting, though scary, facts and statistics about stroke and atrial fibrillation.
Atrial Fibrillation and Stroke Facts
- Each year, about 700,000 people have a stroke in the U.S., with about 500,000 being first attacks. 2
- About every 45 seconds someone in the U.S. has a stroke. 2
- Atrial fibrillation accounts for 15–20% of strokes in the U.S. (105,000–140,000 per year). 2
- Atrial fibrillation patients have a five-fold increase in stroke risk. 3
- About 35% of atrial fibrillation patients will have a stroke during their lifetime. 4
- Atrial fibrillation patients with certain heart conditions, such as mitral stenosis, myocardial disease, and sick sinus syndrome, are at highest risk for clots. 5
- Atrial fibrillation increases with age, doubling each decade after age 55. 4
- Women account for 61 percent of U.S. stroke deaths. 2
- Women have a higher risk of death from atrial fibrillation. 2
As an atrial fibrillation patient, you are at significant risk of stroke, especially if your afib is untreated or uncontrolled. Since most of the clots that originate in other parts of the body are formed during atrial fibrillation, 1 your doctor may put you on an anticoagulant, such as warfarin (Coumadin®), to prevent the formation of blood clots. If you are on an anticoagulant, it is critical to maintain control of your blood thickness to prevent clots.
The left atrial appendage of the heart is a major source of these clots. Over 90% of strokes due to blood clots originating in other parts of the body come from clots formed in the left atrial appendage. 6 Thus, the left atrial appendage is now frequently removed as part of surgical ablation for atrial fibrillation patients in order to prevent the clots that cause strokes.
If you already have heart disease, the onset of atrial fibrillation should be of even more serious concern to you, prompting you to take action immediately.
1 Heart and Stroke Facts <www.americanheart.org/presenter.jhtml?identifier=3000333>, American Heart Association, [Internet], Copyright, 1992-2003.
2 "Heart Disease and Stroke Statistics — 2007 Update" <http://www.americanheart.org/presenter.jhtml?identifier=1928>, American Heart Association [Internet], Copyright, 2007.
3 "Arrhythmias Originating in the Atria" <http://www.heart.org/presenter.jhtml?identifier=10>, American Heart Association [Internet], Copyright, 2006.
4 Blackshear, Joseph L., MD, "Appendage Obliteration to Reduce Stroke in Cardiac Surgical Patients With Atrial Fibrillation" <http://ats.ctsnetjournals.org/cgi/content/abstract/annts;61/2/755>, The Annals of Thoracic Surgery, 1996;61:755-759
5 "Atrial Fibrillation" <http://www.heart.org/presenter.jhtml?identifier=1596>, American Heart Association [Internet], Copyright, 2006.
6 Johnson, W. Dudley, "The left atrial appendage: our most lethal human attachment! Surgical implications" <http://ejcts.ctsnetjournals.org/cgi/content/abstract/17/6/718>, European Journal of Cardiothoracic Surgery, 2000;17:718-722.
