According to the Heart and Stroke Foundation, 250,000 Canadians currently diagnosed with the most common type of heart arrhythmia - atrial fibrillation (AF) - are at least five times more at risk to have a stroke and twice as likely to die from one. More worrisome is that the vast majority may not be aware of their stroke risk.(1)
"Complicating matters, many Canadians are not being properly treated for the condition in the first place," says Dr. Paul Dorian, Heart and Stroke Foundation spokesperson and cardiologist.
"Up to 15 percent of strokes are caused by AF," adds Dr. Dorian. "In people over the age of 60, that number increases to about one-third of strokes."
Atrial fibrillation (AF), a type of irregular heart rhythm known as an arrhythmia, can cause the heart to beat very fast, sometimes more than 150 beats per minute. While it is rare in people under 40, its prevalence increases with age. After the age of 55, the incidence of AF doubles with each decade of life and with other risk factors for heart disease and stroke including high blood pressure, diabetes and underlying heart disease.
"Stroke places a tremendous burden on our society. When AF patients have a stroke, the impact becomes even more profound," says Dr. Marco Di Buono, director of research, Heart and Stroke Foundation of Ontario. "These patients are reported to stay in hospital longer, have increased disability, and are more likely to have recurrent strokes."(2/3)
A WAKE-UP CALL
"The most important medical advance in the past decade is the effectiveness of blood thinners in managing AF and the risk of having a stroke," says Dr. Dorian. "Yet, it is extremely disturbing that only a small percentage of at-risk patients are actually prescribed these life saving treatments."
Most Canadians living with AF manage their condition by following a healthy lifestyle and taking prescribed medication. While warfarin is the most commonly prescribed medication for reducing stroke risk in the AF patient, its use in Canada by people age 65 and older with the condition remains below 50 per cent.4 The use of anticoagulants such as warfarin prevent clots from forming in the heart and traveling to the brain.
"Clinical guidelines are in place but there is a need for healthcare practitioners to be aware of the condition's risks and put the treatment options into practice," says Dr. Di Buono. "Further, people with AF should talk to their healthcare providers about their stroke risk and what they can do about it."
According to the Heart and Stroke Foundation, a growing body of evidence suggests that AF patients can be better categorized based on their risk for developing stroke as a means of identifying the appropriate therapy. For example, the elderly, those with a previous stroke or TIA (mini stroke), and patients with high blood pressure, diabetes, or heart failure are all at greater risk of suffering from a stroke after being diagnosed with atrial fibrillation.
The CHADS(2) Index is a simple tool used by many healthcare providers to determine stroke risk:
Risk Criteria Points
C - CONGESTIVE HEART FAILURE 1
H - Hypertension (high blood pressure) 1
A - Age (greater than 75 years) 1
D - Diabetes 1
S - Stroke or transient ischemic attack (TIA) 2
How the CHADS(2) Index works: one point is given for each risk condition (age, high blood pressure, diabetes, congestive heart failure). A previous stroke or TIA adds two points to a patients score. The greater the score, the greater the risk of developing stroke. A patient with a score of 0 would have an annual risk of stroke of about 1.9%. The patient with a score of 6 would have about 18% annual risk of stroke.
"Bottom line - stroke is a medical emergency and we know the AF patient is at increased risk of stroke, says Dr. Dorian. "All Canadians, AF patients especially, should know how to recognize and react to stroke warning signs if needed."
WHAT IS THE HEART AND STROKE FOUNDATION DOING
The Heart and Stroke Foundation is concerned about the high incidence of stroke, its impact and economic burden, and has taken a number of steps to address this issue, including:
Heart and Stroke Foundation Recommendations To people with atrial fibrillation:
To healthcare practitioners:
1 AF AWARE Group survey 2009 - Slightly more than 4% of patients are aware of the increased stroke risk that ensues with AF, The survey included 75 patients per country in 11 countries (including Canada.)
2/3 Lin H, Wolf P, Kelly-Hayes M, et al. Stroke severity in atrial fibrillation: The Framingham Study. Stroke 1996;27:1760-4.; Jorgensen HS, Nakayama H., Reith J., Raaschou HO, Olsen TS. Acute stroke with atrial fibrillation. The Copenhagen Stroke Study, Stroke 1998:27:1765-9.
4 Humphries KH, Jackevisius C, Gong Y, Svensen L, Cox J, Tu JV, Laupacis A. Population rates of atrial fibrillation/flutter in Canada. Can J Cardiol 2004;20:869-76