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Pressure test predicts need for angioplasty

DALLAS– The pressure of blood flow through moderately clogged arteries, rather than the amount of blockage, may be more indicative of which individuals need balloon angioplasty, researchers report in today’s Circulation: Journal of the American Heart Association.

A coronary angiogram – a diagnostic X-ray examination of the heart – is often used alone or in combination with exercise stress tests, to determine whether individuals with chest pain should have percutaneous transluminal coronary angioplasty (PTCA), also known as balloon angioplasty. This procedure involves inserting a balloon-tipped catheter into a clogged artery to widen it. However, because an angiogram is a two-dimensional picture, a cardiologist often cannot tell how serious a moderate narrowing may be.

“The narrowing may seem mild on the angiogram, but in reality, may be much more severe,” says senior author Nico H. J. Pijls, M.D., Ph.D., professor of cardiology at Catharina Hospital in Eindhoven, The Netherlands. “It is not the anatomic appearance of the narrowing that is important, but the impeding of coronary blood flow.” Doing an unnecessary angioplasty carries several risks, including the potential for accelerating atherosclerosis and the chance that the treated artery will close off completely, which might cause a disabling or fatal heart attack.

In an international study, Pijls and colleagues investigated whether a catheter test to measure the pressure of blood flow in an artery given at the time of coronary angiography might help physicians decide how best to handle individuals with only moderate artery blockage.

The test measures fractional flow reserve (FFR) – the pressure of blood flow through a coronary blockage compared to the normal pressure of blood flow. A person with a FFR of 0.75 has 75 percent of normal flow pressure. Previous research has indicated that those with a FFR below 0.75 should undergo either angioplasty or coronary artery bypass surgery.

This study included 325 patients without documented evidence of ischemia – an inadequate supply of oxygen to the heart due to narrowing of coronary arteries – who were scheduled to have elective angioplasty based on a previous angiography examination. Those with blockages that did not impede blood flow, as evidenced by a FFR of 0.75 or greater, were randomized to two groups. Ninety underwent angioplasty, and were called the performance group, while 91 people who did not have angioplasty were the deferral group. Individuals with an FFR of less than 0.75 had the procedure, and were called the reference group (144 people).

The groups were followed periodically and at the end of two years, researchers had complete data on 317 (98 percent) of them. Patients in the deferral group and the performance group had statistically similar outcomes, although the numbers were slightly better among those who did not have angioplasty.

At two years, 89 percent of those in the deferral group versus 83 percent of those in the performance group were event-free, meaning they had not died of heart disease, suffered a nonfatal heart attack, undergone angioplasty or coronary bypass surgery, or had a treatment-related complication that required major therapy or a long hospital stay. Seventy-eight percent of those in the reference group were event-free.

“In patients whose hearts receive an adequate blood supply despite their atherosclerosis, there is no benefit from angioplasty, either in their symptoms or in terms of fewer deaths, heart attacks, or subsequent coronary bypass operations or angioplasty procedures,” says Pijls. “On the other hand, if blood supply is inadequate, as indicated by the pressure measurement, angioplasty is appropriate, and results in a long-lasting dramatic improvement of symptoms.”

In an accompanying editorial, Robert F. Wilson, M.D., professor and director of cardiac catheterization at the University of Minnesota, calls the research a landmark study that should guide clinicians in selecting who needs intervention and who is better left alone.

These researchers demonstrated in a randomized trial that a decision not to widen moderately clogged arteries that do not limit blood flow, despite what an angiogram may indicate, “is safe and provides an outcome equal to or better than angioplasty,” he writes.

Wilson suggests that measuring FFR should allow doctors performing coronary angiograms to decide more precisely who needs angioplasty or bypass surgery. Additionally, by measuring FFR during the angiogram, a decision to perform angioplasty can be done during the same procedure.

The first author is G. Jan Willem Bech, M.D. and co-authors are Bernard De Bruyne, M.D., Ph.D.; Ebo D. de Muinck, M.D., Ph.D.; Jan C. A. Hoorntje, M.D., Ph.D.; Javier Escaned, M.D., Ph.D.; Pieter R. Stella, M.D.; Eric Boersma, M.Sc., Ph.D.; Jozef Bartunek, M.D., Ph.D.; Jacques J. Koolen, M.D., Ph.D.; and William Wijns, M.D., Ph.D.

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