Dear Doctor:

Help! I just saw on TV that half of all Americans now have heart disease. How did this happen? How do I know if I’m one of the 50 percent?

Dear Reader: You’re referring to a new report from the American Heart Association, which was published at the start of this year. The statistical update concluded that at least 48 percent of American adults have some sort of cardiovascular disease. Individuals under the age of 18 were not included in the report, so it’s not actually half of all Americans. The update, which is released at the start of each new year, is compiled in collaboration with a number of government agencies, including the National Institutes of Health.

To understand why this number is suddenly so high, we need to rewind to 2017. That’s when the joint American Heart Association-American College of Cardiology hypertension guidelines got an update. At that time, the definition of high blood pressure was lowered from 140/90 mm Hg to 130/80 mm Hg. In one fell swoop, millions of Americans who thought they had normal blood pressure the day before were suddenly in the hypertensive category.

Some of you may remember that this change to the definition of high blood pressure proved to be controversial. The lower benchmark was based on a medical trial in which the method of measuring blood pressure was markedly different from what you’ll typically undergo in a medical setting. Participants were allowed to sit quietly for several minutes before an automated device was used to measure their blood pressure. The final reading was derived from the average of up to three separate measurements. This all led to some robust debate in the medical community.

Another factor in the new heart disease estimates is the definition of cardiovascular disease itself. It includes heart failure, stroke, coronary heart disease, and yes, high blood pressure. That means anyone with a blood pressure reading of 130/80 mm Hg or higher now meets the definition of heart disease. But when you exclude high blood pressure and focus solely on the other three conditions, the prevalence of cardiovascular disease among American adults drops to 9 percent overall.

Still, high blood pressure is dangerous. Not only is it the most common risk factor for stroke and heart disease, it plays a role in a number of other serious health conditions. The challenge is that high blood pressure is a silent condition. You can’t feel it. But inside the body, all sorts of bad things are happening. Over time, uncontrolled high blood pressure can damage and weaken arteries, the heart and blood vessels in the brain. The blood vessels in the eyes and kidneys are also at risk. Research continues to show a connection between high blood pressure and certain types of cognitive impairment and dementia. That’s why, through lifestyle changes, medication or both, controlling blood pressure is important to good health.

As for learning about the status of your own heart health, the best way is to see your primary care physician. Through a physical examination and certain tests, including a blood pressure reading and a lipid profile, you’ll learn where you stand.