The technique, called magnetic resonance angiography (MRA), was almost as effective as the standard coronary angiography method in looking at the results of bypass operations, a group led by Dr. Ernst E. van der Wall, professor of cardiology at Leiden University Medical Center, reports in the Jan. 22 issue of Circulation: Journal of the American Heart Association.
The standard way of determining whether blood vessels in the heart arteries are working is through coronary angiography, in which a thin catheter is threaded into the heart so that an X-ray film can be made. That procedure requires at least a one-day hospital stay and runs the risk that the catheter can damage a blood vessel.But MRA, which uses computer technology, radio waves and high-intensity magnetic fields to get images of body tissues, can be done without a hospital stay and at half the cost of conventional angiography, van der Wall says.
In a study of 56 blood vessel grafts in 38 patients who had undergone bypass operations, "the high-resolution images were comparable to images obtained with X-ray angiography," van der Wall says.
New MRA technology makes those results possible, he adds. "We can visualize coronary arteries better and better. The blood vessels have a two-millimeter cross-sectional area, and we now have technological capabilities that allow sub-millimeter scanning."
All the patients in the study had complained of chest pain after surgery, a warning sign that more intervention might be needed. They all volunteered to have MRA in addition to conventional angiography. In most cases, the diagnostic accuracy of the MRA results, compared to conventional angiography, was better than 80 percent.
"This technology is beginning to compete with invasive angiography," says Dr. Valentin Fuster, professor of medicine at Mount Sinai School of Medicine in New York and a past president of the American Heart Association. "It is beginning to compete not only because of its friendliness but also because it is cheaper."
MRA has "many, many possibilities, not only in the coronary arteries," Fuster adds. "It will allow us to look at the function of the muscles of the heart and the structure of the heart."
The technique now is being used in Leiden to help determine whether patients need bypass surgery, van der Wall says. "We can do flow mapping, so we can determine coronary flow both at rest and under conditions of stress to indicate whether we need to operate on patients."
Advanced MRA equipment now is available commercially, van der Wall says. "Each of the companies that produce magnetic resonance equipment can deliver it to institutions," he says.
Fuster notes that "this is not a simple technology. It requires expertise in addition to appropriate equipment." But several medical centers are working on enabling MRA to give highly detailed images of heart arteries, he says.
Some of those results are expected to be reported next week at the annual meeting of the Society of Cardiovascular Magnetic Resonance in Orlando, Fla., van der Wall says. His group will present its latest results there, he adds.
What To Do
Patients can ask whether MRA technology is available for assessment of their arteries.