May 30, 2014
News Review From Harvard Medical School -- Systolic Pressure Linked to More Problems
The risk of future health problems for people with high blood pressure depends on which type they have, a new study shows. Systolic pressure is the top number in a blood pressure reading. Diastolic is the bottom number. In the study, high systolic pressure (140 or more) was linked with the most problems. Researchers looked at health records for more than 1 million people. They were at least 30 years old and did not have heart disease when the study began. Researchers kept track of them for about 5 years. People with high systolic blood pressure were more likely to have bleeding strokes, stable angina (chest pain) and narrowed arteries in the legs. High diastolic pressure (90 or more) was linked only with abdominal aortic aneurysm. This is a swelling of the body's largest artery in the belly area. Researchers estimated that a 30-year-old with high blood pressure would have a 63% lifetime risk of developing heart disease. The risk would be 46% for someone with normal blood pressure. Someone with high blood pressure also would develop the disease about 5 years sooner, the study found. The journal Lancet published the study. HealthDay News wrote about it May 30.
By Howard LeWine, M.D.
Harvard Medical School
What Is the Doctor's Reaction?
In the past, doctors didn't pay attention to the top number of a blood pressure reading. That's the systolic blood pressure. It's the pressure that the heart produces when it pumps blood. All of the focus was on the bottom number, the diastolic blood pressure. That's the pressure in your blood vessels when the heart is at rest.
So treatment for high blood pressure (hypertension) was aimed at keeping the diastolic pressure under 90. People who had only a high systolic reading did not get treatment to lower blood pressure.
In the 1980s, experts started telling us that both numbers were important. And more studies suggested that a high systolic pressure might even cause more strokes and heart disease than a high diastolic pressure.
This new analysis supports the greater significance of a high systolic pressure compared with only a high diastolic pressure. The researchers used 140 or higher to define high systolic pressure and 90 or higher to define high diastolic blood pressure.
The researchers analyzed more than 1 million electronic health records of people age 30 and older. They did not have any history of heart disease, stroke or blood vessel disease. About 20% of them were taking medicines to lower blood pressure at the time of the first record review.
The records were reviewed again several times over a median of 5.2 years. Researchers were looking for a first event of any of the following:
- Heart disease (angina, heart attack or heart failure)
- Abdominal aortic aneurysm (bulging aorta in the belly)
- Peripheral artery disease (narrowed arteries in the legs that cause pain with walking)
Using the data, the researchers calculated the risk of one of these events happening for people with various blood pressure levels.
High diastolic pressure was linked only with a greater risk of an abdominal aortic aneurysm. Heart disease, stroke and peripheral artery disease were linked with high systolic pressure.
Even today, with many good drugs available to treat it, a blood pressure of 140/90 or higher means a substantial risk of heart disease, stroke and blood vessel disease. For a 30-year-old with high blood pressure, the lifetime risk of developing one of these conditions was estimated at 63%. Risk was 46% for a 30-year-old with normal blood pressure. And low-normal pressures, less than 115/75, at age 30 meant an even lower risk later on.
The researchers also calculated the years that people spent free of heart disease, stroke or blood vessel disease related to high blood pressure. On average, a 30-year-old with high blood pressure is likely to develop one of these problems 5 years sooner than if he or she had normal blood pressure.
What Changes Can I Make Now?
Know your blood pressure. If it's normal, check it once or twice a year. Take advantage of any chance you have to get your blood pressure checked. For example, many pharmacies have blood pressure devices that you can use for free.
Normal blood pressure is a reading of no higher than 120/80. Readings between 120/80 and 139/89 show that you have prehypertension. This means you are at risk of developing high blood pressure. More importantly, your risk of heart disease, stroke and blood vessel problems is higher than normal even if your blood pressure doesn't go any higher.
Recent guidelines suggest the blood pressure goal for some people can be 150/90. But it's still best to consider 140/90 or above as high blood pressure that needs treatment. That doesn't mean you need medicine right away. Lifestyle changes might be enough.
Here are the basics:
- Strive for 45 to 60 minutes of exercise a day.
- Increase your overall physical activity throughout the day. For example, walk around within the office or outside your home. Take the stairs rather than the elevator.
- If needed, lose weight. Even 10 pounds can lower blood pressure significantly.
- Load up on fruits and vegetables.
- Cut back on salt.
- Get enough sleep.
- If you drink alcohol, use it in moderation. This means no more than an average of 2 drinks per day for men and no more than 1 per day for women.
- Don't smoke.
Even if these lifestyle changes don't lower your pressure, you likely will need fewer pills and lower doses to reach your goal.
What Can I Expect Looking to the Future?
Fortunately, doctors have lots of medicine choices to lower blood pressure. But just getting to a lower number is not the ultimate goal. Clearly, treating high blood pressure lowers your risk of heart disease, stroke and kidney damage. However, even when treatment has brought your blood pressure readings back into the normal range, having high blood pressure still puts you at higher risk for these conditions.
We need more studies to determine which of our present blood pressure drugs will work best to prevent these health problems. And in the future, you can expect even better drugs to be discovered.