Diagnostics & Imaging Week

A research team at the Mayo Clinic (Rochester, Minnesota) used a non-invasive tool, called an arterial tonometer, to discover an association between stiffness in arteries and the presence and amount of coronary artery calcium, which the clinic said could lead to the accurate assessment of heart disease risk in adults with no symptoms.

Iftikhar Kullo, MD, of the Mayo Clinic and lead author of the study, told Diagnostics & Imaging Week that the test is for people determined to be at intermediate risk based on risk factors outlined by the guidelines published by the National Cholesterol Education Project and assessed a score based on the Framingham Risk Score.

"About 40% of the American public is considered to be at moderate risk for heart disease," said Kullo in a prepared statement. "Nearly half the heart attacks come without warning, which means we need to do a better job of screening people. This test has that potential."

The study was published in the current edition of Hypertension, a publication of the American Heart Association (Dallas).

The test, which is called aortic pulse wave velocity (aPWV), measures how fast the pulse wave travels down the aorta, or the major artery arising from the heart. Mayo said it is a potential screening tool because it is quick, taking only 10 to 15 minutes, painless and likely to be less expensive compared with other cardiac screening tests.

For the test, the patient lies on a bed and a tonometer is placed on the skin over the carotid artery in the neck and then the femoral artery, which is located in the upper thigh. The tonometer measures the pressure wave inside the artery, and the information is fed into a computer for calculation of aPWV.

Kullo said a slower pulse means the artery is more elastic and healthier, while a faster wave means the artery is stiffer and less healthy.

"If you have an electrocardiogram running [simultaneously] . . . then you can tell from when the heart pumps blood [where] it is at a particular phase in the electrocardiogram when the actual pressure wave reaches a particular artery," Kullo told D&IW.

To get a measurement, one measures the onset of the time of the blood in the heart to cycle to the waveform, he said.

"So if you subtract that time delay, that's the time portion of this equation, and then the distance is simply measured by a measuring tape from the heart to the groin; [and] then we have time, we have distance, so we calculate the velocity, and that's the aortic pulse wave velocity," Kullo said.

Researchers tested 401 patients, including 213 men and 188 women, between the ages of 32 and 84 – none of whom had a history of heart attack or stroke – for the research conducted between 2002 and 2004. The median age was 60. The study used a device called the SphygmoCor System by AtCor (West Ryde, Australia).

The research found that study participants with stiffer arteries had a greater amount of calcium in the coronary arteries, an indicator of atherosclerosis.

"Previous research showed an APWV predicts cardiovascular disease in older adults, but the association of aPWV and the amount of coronary artery calcium (CAC) in the general population had been "unknown," Kullo said.

Kullo also said the association between artery stiffness and CAC "strengthens the case for using aPWV as a screening tool," such as in adults with moderate risk, those with a family history of heart disease, patients with high blood pressure and those with kidney disease.

In addition to publication, Kullo said Mayo hopes that his particular non-invasive test will ultimately become part of a panel of non-invasive tests: the first test would be the aPWV; the second test would relate to endoluminal function to ensure that the lining of the vessels is healthy; while the third test would be designed to assess plaque in the carotid arteries.

"What we're hoping is that we [can] try and evaluate the function of the arteries in a comprehensive fashion," he said, later adding, "Between these three tests, we can get a good idea of the health of the arterial system, so that's how we plan to use it."