Factors for Stroke
Risk Factors That Can Be Changed
The most important risk factors for stroke are hypertension, heart disease, diabetes, and cigarette smoking. Others include heavy alcohol consumption, high blood cholesterol levels, and illicit drug use. People with more than one risk factor compound their destructive effects and create an overall risk greater than the simple cumulative effect of the individual risk factors.
High Blood Pressure (Hypertension)
Of all the risk factors that contribute to stroke, the most powerful is hypertension, or high blood pressure. People with hypertension have a risk for stroke that is four to six times higher than the risk for those without hypertension. Forty to 90 percent of stroke patients have high blood pressure before their stroke event.
Persistently high blood pressure greater than 140 over 90 leads to the diagnosis of the disease called hypertension. The impact of hypertension on the total risk for stroke decreases with increasing age, therefore factors other than hypertension play a greater role in the overall stroke risk in elderly adults. For people without hypertension, the absolute risk of stroke increases over time until around the age of 90, when the absolute risk becomes the same as that for people with hypertension.
Antihypertensive medication can decrease a person's risk for stroke. Recent studies suggest that treatment can decrease the stroke incidence rate by 38 percent and decrease the stroke fatality rate by 40 percent.
To learn more about hypertension and how
to manage it, see hypertension in
After hypertension, the second most powerful risk factor for stroke is heart disease, especially a condition known as atrial fibrillation. Atrial fibrillation is irregular beating of the left atrium, or left upper chamber, of the heart. In people with atrial fibrillation, the left atrium beats up to four times faster than the rest of the heart. This leads to an irregular flow of blood and the occasional formation of blood clots that can leave the heart and travel to the brain, causing a stroke.
Atrial fibrillation increases an individual's risk of stroke by 4 to 6 percent. About 15 percent of stroke patients have atrial fibrillation before they experience a stroke. The condition is more prevalent in the upper age groups. The influence of atrial fibrillation on total risk for stroke increases powerfully with age. In people over 80 years old, atrial fibrillation is the direct cause of one in four strokes.
Other forms of heart disease that increase stroke risk include malformations of the heart valves or the heart muscle. Some valve diseases, like mitral valve stenosis or mitral annular calcification, can double the risk for stroke, independent of other risk factors.
Heart muscle malformations can also increase the risk for stroke.
Patent foramen ovale (PFO) is a passage or a hole in the heart wall
that separates the two upper chambers of the heart. Clots in the blood are usually filtered out by the lungs, but PFO could allow emboli or blood clots to bypass the lungs and go directly through the arteries to the brain, potentially causing a stroke.
Atrial septal aneurysm (ASA), a congenital (present from birth) malformation of the heart tissue, is a bulging of the heart wall into one of the atria of the heart.
PFO and ASA frequently occur together and therefore amplify the risk for stroke.
Two other heart malformations that seem to increase the risk for stroke for unknown reasons are left atrial enlargement and left ventricular hypertrophy. People with left atrial enlargement have a larger than normal left atrium of the heart; those with left ventricular hypertrophy have a thickening of the wall of the left ventricle.
Another risk factor for stroke is from the cardiac surgery to correct heart malformations or reverse the effects of heart disease. During this surgery or as a result of this surgery, plaques can get dislodged from the aorta. These may travel through the bloodstream to the arteries in the neck and head, causing stroke. Cardiac surgery increases a person's risk of stroke by about 1 percent.
Other types of surgery can also increase the risk of stroke.
Source: National Institutes
Caution: If you suspect a
stroke, seek emergency medical treatment immediately. Time is of