WASHINGTON (AP) â€” Many doctors are failing to adequately treat patients with high blood pressure because they still believe the top number in a person's blood pressure reading is less important than the lower figure, the National Institutes of Health says.
In an advisory to physicians Thursday, the federal health officials said a high systolic reading is a major underemphasized threat, particularly for older people, even if their diastolic pressure, the bottom number, is normal.
``Unfortunately, many physicians have not yet ... become aggressive in treating such patients,'' said Dr. Daniel Levy, director of the National Heart, Lung and Blood Institute's massive Framingham Heart Study and co-author of the advisory.
An estimated 50 million Americans have high blood pressure, often called the ``silent killer'' because it may not cause symptoms until the patient has suffered serious damage. It raises the risk of heart attacks, strokes, congestive heart failure, kidney damage, blindness and dementia.
Blood pressure is measured as two values. Systolic, the first or top number, is the pressure inside arteries when the heart beats. Diastolic, the last number, is the pressure between beats when the heart relaxes.
Ideal blood pressure is 120 over 80, or lower.
High blood pressure is above 140 over 90.
But even if your bottom number is normal or low, you need to get your systolic pressure below 140, said Dr. Daniel W. Jones of the American Heart Association.
Only one-fourth of hypertension sufferers have their condition adequately controlled. Inadequate control of systolic pressure is the biggest problem, says the NIH advisory, which updates previous federal hypertension guidelines and marks the start of an Internet-run education campaign for doctors and consumers.
The address: http://www.nhlbi.nih.gov.
Millions don't know they have high blood pressure. Others don't properly take their daily medication.
But another reason: For decades, doctors thought diastolic pressure was the only important measurement, and that it was normal for systolic pressure to rise as people aged, said Jones, hypertension chief at the University of Mississippi Medical Center.
Now scientists know that's wrong.
Younger people may have hypertension where just the bottom number, the diastolic pressure, is too high â€” and that is a disease that needs treating.
But usually both numbers rise or â€” most common after age 60 â€” just the systolic pressure is high while the diastolic is normal or even falls, says Thursday's advisory by the NIH heart institute.
So if your pressure is, say, 170 over 70, that's called ``isolated systolic hypertension'' and it needs treatment, Levy said.
In one recent study, patients properly treated for isolated systolic hypertension cut their risk of heart failure by more than 50 percent and the risk of stroke and heart attacks by a third. ``That's a pretty dramatic lowering of risk,'' Levy said.
Another example: Say your pressure is 160 over 100, and a first attempt at medication drops it to 148 over 86. Sometimes doctors figure the bottom number is low enough to stop treatment, but ``you need to press on until you get the systolic to less than 140,'' Jones said.
Some people need even more stringent blood pressure control. The NIH advisory recommends that diabetics, who already are at risk for heart disease, keep blood pressure below 130 over 85.
Hypertension treatment is the same regardless of whether the problem is systolic or diastolic or both. Diet and exercise may be enough for some people. Others may need one or more medications.