Novel technique for measuring blood flow restriction shows promise

A novel, minimally invasive method of determining whether fatty deposits in a coronary artery are restricting blood flow to a patient’s heart performed similarly to the standard, more-invasive procedure in a large multicountry European randomized trial presented at the American College of Cardiology’s Annual Scientific Session (ACC.26). The study was simultaneously published online in the New England Journal of Medicine.

The technique is one of several minimally invasive approaches in development that could make this technology available to more patients and ultimately improve outcomes for patients with serious heart disease.

“Our new method produced very similar outcomes at one year compared with the standard of care,” said

Joost Daemen, MD, Ph.D., associate professor in the Department of Cardiology at the Erasmus University Medical Center in Rotterdam, Netherlands, and first author of the study. “We have also shown that this technique can easily be incorporated into routine clinical practice.”

In coronary artery disease (CAD), fatty deposits known as plaques develop in the walls of the arteries that carry blood to the heart, narrowing the artery and potentially restricting blood flow. Fractional flow reserve (FFR) is a technique for measuring blood pressure and flow within a coronary artery to help cardiologists evaluate to what extent plaques in the artery are restricting blood flow to the patient’s heart.

FFR helps to determine whether the patient will benefit from percutaneous coronary intervention (PCI), also known as angioplasty, in which a tiny balloon is placed inside the artery and a small, wire-mesh tube called a stent is placed at the site of the blockage to prop the artery open and keep it from becoming blocked again.

To perform FFR, physicians first give the patient a drug that increases blood flow to the heart. Then they thread a wire or catheter into the blocked artery to measure blood flow and pressure. Although research supports the benefits of FFR and it is recommended in treatment guidelines, use of the procedure remains low.

Researchers have said this may be due to the procedure’s cost, technical complexity and potential complications, as well as the additional time needed to do it and the need to medicate the patient.

Several less-invasive FFR methods are being tested in clinical trials. In general, these novel methods use sophisticated computer software to evaluate whether a blockage in a coronary artery restricts blood flow to a patient’s heart, eliminating the need to medicate the patient or insert a wire or catheter into the artery.

Vessel FFR (vFFR) is a novel technique that uses computer analysis of three-dimensional images from a coronary angiogram (a heart X-ray) to calculate the severity of blood-flow restriction through an artery that’s narrowed by plaque, Daemen said.

The FAST-III trial was designed to assess whether vFFR produced similar results to conventional FFR in patients with intermediate coronary artery lesions in need of physiological assessment.

The trial enrolled 2,235 patients (average age 67 years, 24% women) in seven European countries. Most patients (81%) reported experiencing chest pain with physical exertion or stress, while 19% either presented with a heart attack or were at high risk for one due to intense chest pain. More than 70% of the patients also had high cholesterol, high blood pressure or both; about a quarter had diabetes; and about a third had undergone a previous PCI.

Patients were randomly assigned to receive either conventional FFR or vFFR. Patients with positive test results were subsequently treated with PCI or bypass surgery.

The trial’s primary endpoint was a composite of death from any cause, a heart attack or any other procedure to restore blood flow to the heart, at one year. The key secondary endpoint, study vessel failure, was a composite of cardiac death, a heart attack or any other procedure to restore blood flow to the heart due to an event that occurred in a blood vessel that had been assessed by either conventional FFR or vFFR.

In both groups, 7.5% of patients experienced a primary endpoint event. The key secondary endpoint of study vessel failure occurred in 4% of patients in the vFFR group vs. 4.6% in the conventional FFR group.

A limitation of the study is that it was not blinded, Daemen said—that is, patients and treating physicians knew whether patients had received conventional FFR or vFFR. Another limitation is that only 19% of the patients presented with a heart attack.

As a next step, Daemen and his colleagues plan to analyze whether vFFR generates cost savings compared with conventional FFR.