Young adults who seem to be healthy, but have a clustering of heart disease risks factors known as metabolic syndrome, tend to have signs of thickening of their carotid artery walls, which is an early indication of atherosclerosis, according to a new study in the Aug 2, 2005, issue of the Journal of the American College of Cardiology.
“What was surprising is how the constellation of abnormalities in patients with metabolic syndrome worked together to create a significant degree of subclinical atherosclerosis in individuals so young. They were only 32 years old on average, but if they had the metabolic syndrome, they were more likely to have thickening of the carotid walls expected in subjects who were much older - indicating that their arteries were “aging” more quickly. This provides a powerful message that maintaining healthy habits should be a lifelong venture. It also shows that risk factor assessment and modification, if needed, should begin much earlier than in middle age,” said James H. Stein, M.D., F.A.C.C., at the University of Wisconsin Medical School in Madison.
The researchers, including lead author Wendy S. Tzou, M.D., studied 507 young adults (20 to 38 years old) who were participants in the Bogalusa Heart Study, which is a long-running heart health study following healthy white and African-American children and adults in Bogalusa, Ala.
Using ultrasound, the researchers measured the thickness of the inner layers of the carotid arteries. Carotid intima-media thickness can identify subclinical atherosclerosis, that is, hardening and thickening of the arteries before an individual feels any symptoms. The artery wall thickness is a predictor of cardiovascular risk.
The study participants were also classified as having metabolic syndrome if they met a set of criteria that included combinations of large waists or high body-mass index, elevated triglycerides, low HDL (“good”) cholesterol, elevated blood pressure and elevated blood sugar or insulin levels.
“Metabolic syndrome has been shown to be associated with atherosclerosis and increased cardiovascular risk among middle-aged and older adults. However, this is the first study to demonstrate that metabolic syndrome is associated with increased subclinical atherosclerosis in otherwise healthy young adults,” Dr. Stein said. “Those with the thickest carotid artery walls were two to three times more likely to have metabolic syndrome, independently of age, sex, race and smoking status.”
The authors wrote that the results support screening and early intervention among young people with metabolic syndrome, even if they feel healthy.
“The most important screening tools are simple to use and have been outlined by several established guidelines. They include measuring blood lipid levels (cholesterol and triglycerides) at 20 years of age or older, assessing blood pressure at every visit, checking smoking status and addressing other lifestyle-related risk factors such as diet, activity level and overweight status,” Dr. Stein said. “The key, however, is to respond to any observed abnormalities with lifestyle changes, and if necessary, pharmacological therapy. Watching and waiting for cardiovascular events to occur is a disastrous approach. Our study shows that the blood vessel injury occurs at a pretty young age.”
Dr. Stein noted that this study was a snapshot that looked at markers for atherosclerosis, rather than heart attacks or strokes. He said it would be useful to follow the study participants in order to see if those with metabolic syndrome ultimately suffer more heart attacks, strokes and deaths.
David G. Meyers, M.D., M.P.H., F.A.C.C., at the University of Kansas Medical Center in Kansas City, Kan., who was not connected with this study, called it a well-performed statistical analysis.
“The Bogalusa Heart Study has been key in demonstrating that atherosclerosis development begins post-puberty. The researchers now show that metabolic syndrome in youth marks individuals at particularly high risk. Ideally, one could use this information to target risk factor modification, such as weight loss and lipid modification. Primary prevention trials suggest that this is possible,” Dr. Meyers said.
More information on the Bogalusa Heart Study is available at www.som.tulane.edu/cardiohealth/bog.html.
The American College of Cardiology, a 33,000-member nonprofit professional medical society and teaching institution, is dedicated to fostering optimal cardiovascular care and disease prevention through professional education, promotion of research, leadership in the development of standards and guidelines, and the formulation of health care policy.