Vascular age: You’re only as old as your arteries

The number of candles on your birthday cake may add up to your chronological age, but it doesn’t necessarily equal your biological age: environmental factors, such as stress and diet, and genetics can speed up or slow down how the body ages.

For this reason, cardiologists at the University of Wisconsin Medical School have developed mathematical equations that can calculate a person’s vascular age. This number, say the researchers, provides a more accurate and understandable assessment of a person’s risk of developing heart disease, the No. 1 killer of Americans, or of having a stroke, the leading cause of disability in the United States.

Risk-assessment tools for heart disease and stroke already exist, says James Stein, associate director of the UW Health Heart and Vascular Care Preventive Cardiology program, who led the effort to develop the equations. Stein explains that these tools, which calculate risk based on factors such as blood pressure, cholesterol, chronological age and family history, work well for identifying low- or high-risk individuals, but cannot accurately assess the risk of those people who fall somewhere in between.

“A lot of patients fall into an intermediate zone,” says Stein. “They present a clinical challenge when it comes to determining their disease burden and management plan.”

To determine a person’s risk of developing heart disease or having a stroke, Stein and his group turned to ultrasound technology. Non-invasively, they can capture images of the carotid arteries, the chief vessels running up the neck and supplying the brain with blood. Based on the images, they measure the thickness of the artery walls. Thicker walls, says Stein, increase the risk of heart attack or stroke.

Measuring wall thickness as a screening tool, says Stein, is “an old idea” and one recommended by the American Heart Association. But, using this technique in a clinical setting, he adds, is a relatively new approach. The UW Health Heart and Vascular Care program, for example, is the only one in the Midwest that offers this vascular health screening.

“The technique requires sophisticated equipment and extensive technical training,” says Stein.

Using wall thickness measurements determined from the ultrasound images in the new equations, the cardiologists then calculate the “age” of a person’s arteries. For instance, they can determine that a 45-year-old woman whose carotid artery walls are as thick as those of a 65-year-old woman in normal health has a “vascular age” of 65 years.

The numbers can go the other way, too. From clinical research that calculates vascular age, Stein and his group have reclassified about half of the intermediate or “borderline” risk participants into either higher- or lower-risk categories.

Combined with traditional risk-assessment measures, Stein says, “vascular age is a tool that can give clinicians a more precise understanding of a patient’s risk, eliminating some of the uncertainty. It can help us identify and treat people before they have a heart attack or stroke.” Just as important, he says, is using vascular age as “an important communication tool that helps doctors better explain risk to their patients.”

The vascular-age equations are patented by the Wisconsin Alumni Research Foundation, a non-profit agency that manages the intellectual property developed by UW–Madison researchers.

For more information about the ultrasound vascular screening technique offered at UW–Madison, please call (608) 263-9014 or (608) 263-1530, or visit http://www.uwhealth.org. More information can be found under “specialties and programs, heart and vascular care.”