High BP norms revised by American Heart Association: Cardiologist explains why less than 120/80 mm Hg is the new normal

What are the new blood pressure parameters?

Blood pressure, measured in millimetres of mercury (mm Hg), is recorded as two numbers, the systolic (top number) and diastolic (bottom number). The systolic number measures the force of blood pumped by the heart while the diastolic reading measures it when the heart rests between beats.

Compared to the time when 130/90 mmHg was considered the new normal, the AHA now classifies normal blood pressure as <120 mm Hg systolic and <80 mm Hg diastolic. “So the normal level of 120/80 mm Hg has been reduced further. Which means your ideal BP should now be 115-119/70-79 mm Hg,” says Dr Singh.

Elevated blood pressure is now classified as 120 to 129 mm Hg systolic and <80 mm Hg diastolic. Stage 1 hypertension is classified as 130 to 139 mm Hg systolic or 80 to 89 mm Hg diastolic; and stage 2 hypertension as ≥140 mm Hg systolic or ≥90 mm Hg diastolic.

“The aggressive revision has much to do with brain health and avoiding pregnancy-related complications. Research has shown that high BP can damage small blood vessels in the brain, affecting cognitive function,” says Dr Singh.

When should a person start taking BP pills?

“According to the new guidelines, a systolic reading of 130–139 mm Hg should first be managed with lifestyle changes. Medication should be started if it doesn’t reduce after the changes or your diastolic goes up from 80 to 90 mm Hg. A single medication is advised in this case. This is being done to prevent a crisis in heart failure patients, who cannot pump blood as effectively. BP puts further stress,” says Dr Singh.

If the pressure is more than 140/90 mm Hg, the guidelines start with two drugs immediately. “That’s because combining different medications that work through different mechanisms to lower blood pressure can be more effective and sustained than using a single drug at a higher dose,” says Dr Singh.

What tests have been recommended?

The guidelines have reinforced the need for controlling hypertension with tests like liver function test (LFT), kidney function test (KFT), sodium-potassium balance, uric acid and blood sugar profiles. “However, this time guidelines are looking at kidneys and hormones too, making the urine albumin-to-creatinine ratio test (to measure kidney health) and aldosterone-to-renin ratio test (to detect a specific hormone-driven type of high blood pressure) mandatory. These two tests are specific to those who have stage 2 hypertension and other risk factors like sleep apnea. Diabetes, pregnancy and kidney health status will determine how aggressive and early the treatment should be,” says Dr Singh.

He also points out that the role of potassium, be it in salts or diet, has been emphasised for its role in BP control. “The AHA feels that potassium-based salt substitutes can be useful to prevent or treat elevated BP, except in those with kidney disease,” he adds.

What about prevention?

Cliched as they may sound, the AHA repeats what we know for better adherence. Limit sodium intake to less than 2,300 mg per day, moving toward an ideal limit of 1,500 mg per day by checking food labels. Quit smoking and limit alcohol, consuming no more than two drinks per day for men and no more than one drink per day for women. The AHA advises stress management through meditation, breath control or yoga and reducing weight by setting a doable goal of reducing it at least by five per cent. It recommends physical activity of at least 75-150 minutes each week, including aerobic exercise (such as cardio) and/or resistance training (such as weight training).

The AHA re-emphasises the DASH eating plan, which means a diet rich in vegetables, fruits, whole grains, legumes, nuts and seeds, lean meats, poultry and fish and low in fat.

Of course, all of this should be topped up with blood pressure monitoring at home.