Diagnostics & Imaging Week

A small finger-like device could give patients greater insight on their risk for heart disease, according to a study conducted by the Mayo Clinic (Rochester, Minnesota).

The noninvasive finger test device is called the EndoPAT and was developed by Itamar Medical (Framingham, Massachusetts). It measures the health of endothelia cells by measuring blood flow. These cells line the blood vessels and help to regulate normal blood flow.

Researchers at Mayo Clinic and Tufts-New England Medical Center (Boston) used the device to test 270 patients between the ages of 42 and 66 and followed their progress from August 1999 to August 2007. These patients already knew that they had low-to-medium risk of experiencing a major heart event, based on their Framingham Risk Score. The score is the commonly used risk predictor and was developed from the Framingham Heart Study, a longitudinal study of heart disease.

Past research has indicated that if these cells don't function properly, a condition called endothelial dysfunction can occur, and if this happens then this can lead to the hardening of arteries, which can in turn lead to severe heart problems.

Prior to the EndoPat, which received FDA approval nearly four years ago, there was no simple test for endothelium function, says Amir Lerman, MD a cardiologist at Mayo Clinic and the senior author of the study.

Lerman authored the paper with several other Mayo Clinic study team members, including Ronen Rubinshtein, MD; Ryan Lennon; Rebecca Nelson; Geralyn Pumper; and Lilach Lerman, MD, PhD. Team members from Tufts-New England Medical Center are Jeffrey Kuvin, MD, and Morgan Soffler, MD.

"We don't want people to confuse this for a screening tool," Lerman told Diagnostics & Imaging Week. "That is a very dangerous word. The device is more for patients in the intermediate risk for cardiovascular disease . . . for patients [who] have hypertension, high cholesterol or have a family history of heart disease."

Nearly 49% of patients whose EndoPAT test indicated poor endothelial function had a cardiac event during the seven-year study.

Some of their risk factors included high blood pressure, high cholesterol, obesity and a family history of heart disease, Lerman said. "The results of the study may help identify a discriminating tool beyond the Framingham Risk Score," he said. "And the results of these individual tests may help physicians change a patient's medications or recommend other therapies, so they don't have a heart attack or stroke later on."

The test may be used in an individualized medicine model of risk assessment of the patients, Lerman said. "As a clinician I would like to see this test integrated into the clinical setting," he told D&IW.

EndoPAT consists of digital recording equipment and two finger probes that look like large thimbles. For the test, which takes 15 minutes, probes are placed on each index finger and hooked up to a small machine to measure blood flow. A standard blood pressure cuff is placed on one arm; the arm without the cuff is the control.

A reading of the fingers' blood flow rate begins, and then the blood pressure cuff on one arm is inflated for a few minutes and then deflated, allowing for three timed readings.

The role of the inflated blood pressure cuff is to occlude and then release blood flow to assess reactive hyperemia (RH), the normal blood flow response that occurs when occlusion is released. In the study, 49% of the patients who went on to have a cardiac event had a low RH score.

A low RH signal – indicating a lower blood flow response – is consistent with endothelial dysfunction and potentially impaired vascular health that may lead to or serve as a marker for future events.

Lerman said the research team would present the study at the American College of Cardiology's (Washington) annual scientific sessions, which began Saturday in Orlando.

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