Hypertension: Atrial Fibrillation
Longstanding, uncontrolled hypertension coupled with heart disease is the most common cause of the heart rhythm disorder known as atrial fibrillation. People with atrial fibrillation experience periodic spells during which the upper chambers of their hearts quiver erratically. As a result, blood swirls around and pools inside the upper chambers, which may form clots that can cause a stroke if they break loose and make their way to the brain. Experts estimate that atrial fibrillation, which is most common among people over age 65, increases the risk of stroke about fivefold. In the Framingham Heart Study, atrial fibrillation was blamed for one of every four strokes among people over 80. Taking medications that prevent blood clotting, such as warfarin, can reduce the risk of stroke by 67% in people who have atrial fibrillation as well as other stroke risk factors. However, treatment with warfarin carries risks of its own, including the risk of severe bleeding.
Hypertension and diabetes: A dangerous combination
More than three out of four adults with diabetes have blood pressure above 130/80 or are taking hypertensive medication. Like hypertension, diabetes increases your chances of developing heart disease and stroke, as well as kidney disease and eye damage. Having both diabetes and hypertension raises these risks even more.
Although hypertension and diabetes seem to be linked, the mechanism by which they interact is unclear. Some experts theorize that the common denominator may be problems stemming from the body’s production and use of insulin. People with both type 2 diabetes and coronary artery disease frequently have hyperinsulinemia, an excessive amount of circulating insulin. Excess insulin is thought to raise blood pressure in two different ways: by causing the kidneys to retain sodium, and by prompting the sympathetic nervous system to release neurotransmitters that constrict blood vessels.
Over time, most people with diabetes develop cardiovascular problems. Although these are more common among people with type 1 diabetes, they also frequently occur among people with type 2 diabetes. Between 65% and 75% of people with diabetes will die from some type of cardiovascular disease — a death rate that is two to four times that of people without diabetes. Thus, keeping blood pressure in check may be a vital factor in preventing heart disease and strokes among people with diabetes.
Not only are diabetes and hypertension linked to cardiovascular disease, but they can also lead to kidney disease and eye damage. That makes careful control of these conditions even more crucial.
Because of the increased risks associated with hypertension in someone with diabetes, the treatment goal is to lower blood pressure below 130/80 mm Hg. However, a 2010 report in the Journal of the American Medical Association casts some doubt on the benefits of this strategy. The study, which tracked 6,400 people with diabetes and heart disease, found that those who achieved tight control of their blood pressure (less than 130 mm Hg) were no better off than those with usual control (between 130 and 139 mm Hg) in terms of cardiovascular events. Still, an earlier study showed a lower risk of stroke among people with heart disease and diabetes who achieved tight control of their blood pressure, and many physicians still urge such patients to aim for a systolic pressure of less than 130.