This means an estimated 31 million more people could be diagnosed with high blood pressure.
Previously, the AHA said 32 percent of adults in the USA had high blood pressure (hypertension) but with the new guidelines, about 46 percent have hypertension.
The guidelines do not change the definition of normal blood pressure as 120/80 or lower.
Healthy lifestyle changes include losing weight, exercising more, eating healthier, not smoking, avoiding alcohol and salt, and reducing stress.
"We will need tools that help people make informed choices and customize the information to each person", Krumholz added.
Today, millions of Americans who didn't have high blood pressure before have it now.More news: 'No Indication' Saudi Coalition Reopening Yemen Ports
Damage to blood vessels is already beginning once blood pressure reaches 130/80, said the guidelines, which were based in part on a major United States government-funded study of over 9,000 people nationwide.
"The prevalence of hypertension among US adults is substantially higher when the definition in the present guideline is used versus the [older] definition (46% versus 32%)", the authors write.
The category of prehypertension, referring to those with systolic pressure of 120-139, no longer exists.
"It's very clear that their future risk of heart attack and stroke down the road is almost doubled compared to patients with lower numbers", Farrell said.
The proper technique must be used to measure blood pressure, and levels "should be based on an average of two to three readings on at least two different occasions", according to the new guidelines. This is the first time the definition for hypertension has changed in 14 years.
A large, government-sponsored study of hypertension patients aged 50 and older showed in 2015 that death from heart-related causes fell 43 percent and heart failure rates dropped 38 percent when their systolic blood pressure was lowered below 120 versus those taken to a target of under 140.