The percentage of people reporting chest pain dropped in the last two decades among Americans 65 and older and whites 40 and older — but not among blacks, according to a new study.

Angina is chest pain or discomfort that occurs when the heart isn’t getting enough oxygen-rich blood. Symptoms include squeezing in the chest; discomfort in the shoulder, arms, neck, jaw or back; and a feeling of indigestion. It’s usually a symptom of an underlying heart problem or coronary heart disease.

“People often don’t know that they have heart disease until it’s too late,” said Julie C. Will, Ph.D., M.P.H., lead author of the study and a senior epidemiologist at the U.S. Centers for Disease Control and Prevention in Atlanta, Georgia. “Angina serves as a warning to both the patient and the doctor that a person may have underlying heart disease.”

Researchers analyzed national health survey data that started in 1988 to find how many people reported angina symptoms and how many reported a history of the condition after a health worker told them about it.

They found the percentage of people reporting a history of angina from the 2001-04 survey to the 2009-12 survey dropped about a third for whites 40 and older; dropped nearly in half for women 65 and older; and did not change for blacks.

In addition, they found the percentage of people reporting angina symptoms from the 1988-94 survey to the 2009-12 survey declined by half for whites 40 and older; declined by nearly 60 percent for women 65 and older and by more than 40 percent for men 65 and older; and did not change for blacks.

The data is consistent with previous research showing a decline in angina-related hospitalizations and emergency department visits in 1995-2010.

The national data included too few Hispanics and other minorities to reveal angina trends among those groups.

The study was published in the American Heart Association journal Circulation: Cardiovascular Quality and Outcomes.