The percentage of people reporting angina (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 study by researchers at the Centers for Disease Control and Prevention.

Angina occurs when the heart isn’t getting enough oxygen-rich blood and is 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, lead author of the study and a senior epidemiologist at the U.S. Centers for Disease Control and Prevention. “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 starting in 1988 to find how many patients said a health professional told them they have the condition and how many people report angina symptoms.

They found:

• The rates for whites 40 and older reporting a history of angina dropped by about one-third between the 2001-04 survey and the 2009-12 survey.
• The rates for whites 40 and older reporting angina symptoms declined by half from the 1988-94 survey to 2009-12 survey.
• The rates were essentially unchanged for blacks.
• The rates for American women 65 and older reporting a history of angina dropped nearly in half from the 2001-04 survey to the 2009-12 survey.
• The rates for women 65 and older reporting angina symptoms declined by almost 60 percent from the 1988-94 survey to 2009-12 survey. The rates for men in this age group declined by more than 40 percent during this same time period.

“More effective interventions for preventing and controlling high blood pressure, diabetes and smoking cessation may be needed among blacks,” said Dr. Will.

According to the researchers, the national data used for the study included too few Hispanics and other minorities to show angina trends among those groups.

The study was published in  Circulation: Cardiovascular Quality and Outcomes.