Having above optimal levels of risk factors for heart disease between the ages of 18 and 30 can mean a two to three times greater risk of later developing coronary calcium, a strong predictor of heart disease, according to results of a new study from the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health.
Although on average, heart disease risk factors are less common in young adulthood, elevated risk factors levels at this age predict the development of later asymptomatic heart disease better than levels measured later when they are typically higher. Smoking, having an elevated body mass index (BMI), or having above optimal levels of blood pressure, LDL "bad" cholesterol, and blood sugar in early adulthood are linked to the development of calcium deposits in the arteries of the heart 15 years later. Other studies have found that the amount of coronary calcium correlates with the amount of atherosclerosis or hardening of the coronary arteries and is related to the likelihood of developing heart disease in the future. Measuring coronary calcium is a noninvasive way of determining heart disease before it becomes symptomatic.
Results of the Coronary Artery Risk Development in Young Adults (CARDIA) study are published in the April 24, 2007 issue of the Journal of the American College of Cardiology, which is posted online on April 17.
"These findings remind us that we should begin assessing our heart disease risk as early as possible, with a focus on prevention," said Elizabeth G. Nabel, M.D., NHLBI Director. "All of the risk factors we assessed are modifiable. Young adults who achieve and maintain optimal risk factor levels early on could enter middle age with healthy hearts."
The CARDIA study initially measured risk factor levels in 1985 in a group of 5,115 African American and white young adults, ages 18 to 30, who were then followed for 15 years. The study took place in four U.S. cities: Birmingham, Ala., Chicago, Minneapolis, Minn., and Oakland, Calif.
For young adults with above optimal levels of risk factors, the specific risk of developing coronary calcium was:
- Three times greater for those with blood glucose greater than 110 mg/dL compared to those who had glucose levels of 110 mg/dL or lower.
- Two times greater for those with an LDL "bad cholesterol above 130 mg/dL compared to those with 130 or less mg/dL.
- Two times greater for those who smoked compared to those who did not smoke.
- One and a half times greater for those with blood pressure above 120/80 mm/Hg compared to those with blood pressure of 120/80 mm/Hg or less.
- One and a half times greater for those with a BMI over 25 kg/m2 compared to those with a BMI of 25 kg/m2 or less.
Coronary artery calcium was measured through CT scans, computer images of the chest, taken in the fifteenth year of the study, when the participants were ages 33 to 45. Of the 3,043 participants who were scanned, 9.6 percent had detectable coronary artery calcium. Coronary artery calcium was more prevalent among men than women, (15 versus 5.1 percent) and among white men compared with African American men (17.6 versus 11.3 percent). Men and women 40 to 45 years old were twice as likely to have coronary artery calcium than those 33 to 39.
Guidelines for risk assessment call for cholesterol to be measured beginning at age 20, and for blood pressure to be measured every two years in adulthood. Blood glucose should be measured at least every three years beginning at age 45, and earlier for persons at risk.
"As this study illustrates, we are learning more and more about the beginnings of heart disease and how to prevent it," said Catherine Loria, PhD., lead study author and nutritional epidemiologist with NHLBI. "Young men and women should work with their doctors to learn about their risk, and then do everything they can to reduce it, such as eating a healthy diet and being physically active," she added.
To help prevent heart disease, individuals should avoid smoking, seek to achieve and maintain a healthy weight, choose a diet that is low in sodium, saturated fat, trans fat and cholesterol, and get at least 30 minutes of moderate-intensity physical activity on most, or preferably all, days of the week.