Hypertensive studies: 2 results

In December, a study of more than 42,000 white and black Americans found that old-fashioned, cheap diuretics -- “water pills” -- work at least as well and sometimes better than more expensive drugs to treat high blood pressure and certain heart problems. In February, a study of more than 6,000 mostly white Australians came to a different conclusion -- that drugs called ACE inhibitors were better than diuretics, although only for men (for unclear reasons).

Now it falls to a committee of experts picked by the National Heart, Lung and Blood Institute in Bethesda, Md., to reconcile the studies and tell America’s 50 million hypertensives what to do. The conclusions are crucial: Hypertension doubles the risk of heart attack and is the leading risk factor for stroke and heart failure. One in four adult Americans has hypertension, which is defined as a reading of 140/90 or higher.

(The top number is the systolic pressure, taken as the heart muscle contracts; the lower number is the diastolic, as the heart relaxes. Both are measured in millimeters of mercury. Normal blood pressure is 120/80, but even readings of 130/85 should be considered a red flag.)

High blood pressure is so common, especially among older people, that many patients don’t take it as seriously as they should. “High blood pressure doesn’t make you feel bad,” points out Dr. Michele Hamilton, co-director of the heart failure program at UCLA. This makes it harder for people to change their diets, lose weight, reduce stress and take medications.

High blood pressure is also tricky for doctors to treat because they usually don’t know what causes it. In 5% of cases, it’s caused by kidney and adrenal problems, or legal and illegal substances, such as prednisone, cocaine, ephedrine, even licorice. But 95% of hypertension is deemed “essential” or “primary” because the cause is unknown.

Basically, blood pressure is a matter of hydraulics. If the pressure inside artery walls is too low, a person can go into shock and die. If the pressure is too high, because vessels are too narrow or rigid or the heart beats too hard, a person can develop heart and kidney failure and stroke.

The risks increase with age, because blood vessels become more rigid. Data from the institute’s Framingham Heart Study show that a person who has normal blood pressure at 55 has a 90% chance of eventually developing high blood pressure.

Regulation of blood pressure is complex. Short-term fluctuations are controlled by the nervous system, specifically hormones such as adrenaline and noradrenaline. A key player in longer term fluctuations is angiotensin II, a kidney hormone that makes vessels constrict.

If you have hypertension, the first remedy to try is behavioral changes: exercise and nutrition. This means losing weight if you’re heavy, adopting the DASH, or Dietary Approaches to Stop Hypertension, diet and restricting salt. Losing just 10 pounds can lower blood pressure significantly.

It’s not fully clear whether consuming too much salt actually causes hypertension. But age-related increases in blood pressure can be minimized by reducing sodium intake to about 2.4 grams a day -- this equals 6 grams, or 1 teaspoon, of salt. In practice, this means not adding salt when cooking or eating, and avoiding many canned and fried foods, including foods containing soy sauce.

The DASH diet, plus salt restriction, clearly lowers blood pressure. It’s rich in fruits, vegetables, low-fat dairy foods, potassium, calcium, magnesium, fiber and protein. It’s low in total and saturated fat, red meat, sweet foods and sugary drinks.

Stress reduction helps too. Dr. Herbert Benson, president of the Mind/Body Medical Institute and associate professor of medicine at Harvard Medical School, recommends the “relaxation response.” That means taking 10 to 20 minutes a day to meditate, pray or quiet the mind and body through focused concentration. Stress reduction, he says, can minimize the “vicious cycle” in which people panic about their hypertension, making it worse.

If you’ve done all this and still have high blood pressure, you probably need medication. And that’s where doctors disagree -- not on whether medication is needed, but on which drugs to try first. If hypertension is stubborn, you’ll probably need several drugs, and there are many to choose from.

Diuretics such as hydrochlorothiazide (Hydrodiuril) or chlorthalidone (Hygroton) flush excess water and salt from the body, allowing the heart to work less hard. One reason diuretics fared well in the December study -- dubbed ALLHAT -- is that 32% of participants were black. Blacks, perhaps for genetic reasons, tend to be sensitive to salt and hence, highly responsive to diuretics.

Beta-blockers such as propanolol (Inderal) are another staple. They reduce nerve impulses to the heart and blood vessels, making the heart beat more slowly and with less force.

A similar class of drugs is the alpha blockers such as doxazosin (Cardura), which also reduce nerve impulses to blood vessels. But the doxazosin arm of the ALLHAT study was stopped early because those patients had higher rates of cardiac problems.

ACE-inhibitors such as lisinopril (Zestril) relax blood vessels by blocking the formation of angiotensin II. A newer class of drugs called angiotensin antagonists such as losartan (Lotrel) act differently, by blocking receptors for angiotensin II in vessels.

And then there are the calcium channel blockers (CCBs), drugs such as amlodipine (Lotrel). They lower pressure by blocking calcium, which causes vessels to constrict.

Granted, it’s a bit confusing. But it’s reassuring that the ALLHAT study found diuretics to be so effective, says Dr. Sid Smith, past president of the American Heart Assn. and professor of medicine at the University of North Carolina at Chapel Hill.

And because diuretics are cheap -- about 13 cents a pill versus 10 times that for other medications -- “there is no cost-quality trade-off,” as Dr. Lawrence J. Appel, a hypertension specialist at Johns Hopkins Medical Institutions noted in a Journal of the American Medical Assn. editorial.

As to which drug to start with, stay tuned for the findings from the National Heart, Lung and Blood Institute committee. In the meantime, work with your doctor until you find a drug or combination of drugs that get your blood pressure out of the danger zone.