血压,是不是越低越好?
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Blood pressure: How low should you go?
Harvard Men’s Health Watch
A new study suggests greater health benefits with a lower-than-standard number.
Blood pressure has long been one of the best markers of your health. It is a number you can remember and monitor. High blood pressure (hypertension) is linked to a greater risk of heart attacks and strokes.
About one out of three adults has high blood pressure, which is usually defined as a reading of 140/90 millimeters of mercury (mm Hg) or higher.
The first, or upper, number (systolic pressure) represents the pressure inside the arteries when the heart beats, and the second, or lower, number (diastolic pressure) is the pressure between beats when the heart rests.
Blood pressure rises with age because of increasing stiffness of large arteries, long-term buildup of plaque, and the effects of other diseases involving the heart and blood vessels. Typically, more attention is given to the diastolic reading as a major risk factor for cardiovascular disease.
“In fact, for a long time, some physicians felt that a systolic (upper) number higher than 140 could be tolerated in older people,” says Dr. Paul Huang, a cardiologist with Harvard-affiliated Massachusetts General Hospital. “But both upper and lower numbers are equally important.”
A new number to aim for
While 140/90 continues to be the blood pressure cutoff, a study published in the Nov. 26, 2015 issue of The New England Journal of Medicine shows that lowering pressure to around 120/80 may reap greater benefits.
Researchers examined the initial results from the Systolic Blood Pressure Intervention Trial, or SPRINT, which studied 9,361 adults over age 50 who either had hypertension or were at a high risk for cardiovascular disease.
The subjects were divided into two groups. The first received an intensive treatment to lower blood pressure to less than 120/80. The other group followed a standard treatment to lower it to less than 140/90.
After three years, the researchers found that the group with the target of below 120/80 had a 25% lower risk of heart attack, stroke, or cardiovascular death compared with those with the standard target of less than 140/90. They also had 27% fewer deaths from any cause. (The study was stopped early because the outcome in the intensive treatment group was so much better than in the standard treatment group.)
Ups and downs of lower numbers
This study supports observational studies that have found that lower blood pressure reduces cardiovascular risk.
But what does it take to get to the lower numbers? “On average, the people in the intensive treatment group took three blood pressure medications, while those in the standard treatment group only took two,” says Dr. Huang.
Moreover, the study found that the benefits in reducing heart attacks, strokes, and death were found equally in those older or younger than age 75. “So we can no longer say that a higher blood pressure is okay just because someone’s older,” he says.
But should older men focus on going lower? Is lower than 140/90 good enough, or should you be more aggressive and get that number down as close as possible to 120/80?
“If you currently are on blood pressure medicine, and your pressure is lower than 140/90, you should discuss with your doctor whether you should aim to go even lower,” says Dr. Huang. “There may be additional benefits to further reducing your stroke and heart attack risk.”
Still, there may be some downsides to going lower. For instance, many people may not want to take any additional medication. They may be concerned about battling common side effects, such as extra urination, erection problems, weakness, dizziness, insomnia, constipation, and fatigue. They also may have enough trouble monitoring their current medication without adding more to the mix.
Another potential problem: pressure that drops too low. “This could lead to dizziness and lightheadedness, especially when suddenly rising from a seated position, and increase your risk of falls,” says Dr. Huang.
Also, because the study was stopped early, other possible downsides of the extra medications, such as effects on cognitive function or kidney function, remain unknown.
Monitor your blood pressure
If anything, this study reinforces the need for men to be more diligent about maintaining a healthy level, says Dr. Huang. He suggests older men follow these basic guidelines:
Check your pressure every month and alert your doctor to changes. “If the upper number is repeatedly higher than 140, or the lower number higher than 90, let your doctor know,” he says.
Continue to take your medications as prescribed. “If you suffer from any side effects, talk with your doctor about changing the dosage or drug.”
Reduce your salt intake. “You do not have to go sodium-free, but be more aware of how much sodium is in the foods you eat,” he says. In general, try to keep your sodium intake below 2,000 milligrams a day. Foods that include the words “smoked,” “processed,” “instant,” or “cured” in the name or on the label are often quite high in sodium.
Continue to exercise or adopt some kind of workout routine. “Activity and weight loss can help lower and maintain a healthy blood pressure,” says Dr. Huang.
March 1, 2016
