New Charts for Artery Stiffness Could Flag Heart Risk Long Before Symptoms

An international team has created the first comprehensive reference measurements for blood vessel stiffness in healthy young people, a step that could give pediatric and adolescent clinics a multidecade head start in spotting and treating cardiovascular disease risk.

The analysis in Hypertension assembled pulse wave velocity test results from 19,930 participants ages 1 to 40 who met strict "healthy" criteria for blood pressure, body mass index, fasting glucose and cholesterol. The tests measure blood vessel stiffness, i.e., how flexible or inflexible their blood vessels are, because excessive stiffness increases the risk of heart attack or stroke.

"This gives us a tool we did not have," said Vikas Dharnidharka, the Henry Rutgers Professor and Chair of Pediatrics at Robert Wood Johnson Medical School, who is a co-author of the analysis and contributed data to the project. "There's more work to do, but it's the first step in guiding treatment in ways that will save lives."

Pulse wave velocity measures how quickly pressure waves from the heart traverse the blood vessels throughout the body. Stiffer arteries transmit and reflect back the waves faster, when the heart is not ready for its next contraction. Blood vessel walls become stiffer with age. In adults, elevated pulse wave velocity scores predict future heart attacks and strokes independently of other known risks such as high blood pressure or poor lipid panel results. They also indicate which patients need treatments that reduce artery stiffness to protect them from that added risk.

Elevated pulse wave velocity should provide the same added information about the cardiovascular risks of children, adolescents and young adults. However, until now, clinicians haven't been able to detect elevated scores and act upon them because there was no data about what constitutes a healthy score for patients in different age groups.

To build the reference curves for normal scores, the Youth Vascular Consortium, an international research effort dedicated to studying early vascular aging in young people, combined measurements from studies in multiple countries in Europe, Australia, Africa and the Americas. Researchers used statistical models to generate 10th through 90th percentiles by age and sex for six commonly used pulse wave velocity devices. The result looks like growth charts for arteries, with arterial stiffness climbing with age but not stopping at the end of puberty.

The effort required a massive number of patients because each of the six major makers of pulse wave velocity devices uses different algorithms and measurement approaches that provide different numbers.

"It's like VHS and Betamax - or Blu Ray and HD-DVD for those in a younger generation - the devices do the same thing, but they're entirely incompatible," Dharnidharka said. "But they share the market so evenly that we knew we had to establish values for all of them or deny the value of reference ranges to patients whose doctors' devices we hadn't tested."

Despite these complications, pulse wave velocity testing has much to recommend it, he added. The testing is noninvasive and can be performed in a standard exam room with a blood pressure cuff, three electrocardiogram leads and a pencil-like pressure tonometer over the carotid and femoral arteries. Insurers often don't cover it, but clinics can deliver it relatively cheaply.

"I think it was still under $100," Dharnidharka said.

The new charts could influence both triage and treatment. A teenager whose pulse wave velocity sits well above the 90th percentile might prompt closer follow-up or changes in care, particularly when obesity or elevated blood pressure are present. Some blood pressure medications reduce arterial stiffness, while others don't, so pulse wave velocity tests can guide medication selection, Dharnidharka said.

With norms established, research can begin on optimal care for patients with prematurely stiff arteries. Administrative registries and long-running cohort studies - which follow large numbers of patients over time and compare the results produced by different treatments - may be the most realistic way to get there.

"We'll still need registry linkage," Dharnidharka said.

For now, the percentile charts are a crucial foundation. They capture how arterial stiffness normally evolves through childhood and young adulthood. Identifying outliers early could open a window to interventions with bigger downstream payoff.

"This was a critical step," Dharnidharka said.