DALLAS, June 13 - A non-invasive imaging technique may offer clues to the early beginnings of heart disease, according to a study in today's Circulation: Journal of the American Heart Association.
The technique - phase-contrast magnetic resonance (PC-MR) imaging - measures the coronary blood flow and can also assess heart function. The technique is similar to a conventional MRI and may offer physicians new and better ways to identify blood flow problems to the heart muscle.
The study's lead author, Juerg Schwitter, M.D., assistant professor of cardiology at University Hospital of Zurich, Switzerland, says, "I think this technique will prove to be a valuable research tool in developing new medications to prevent the development of coronary artery disease."
In Switzerland, Schwitter and his colleagues are using the technique in drug studies to evaluate whether specific medications can preserve the general blood flow of the heart. Using the results of these studies, Schwitter says physicians may eventually be able to use these medications to boost coronary blood flow early in the disease process, thereby stemming its progression.
PC-MR has been used for flow measurement in blood vessels since the mid-1980s and is considered the "gold standard" for such measurements, according to Schwitter. What's new about this study, he says, is that the imaging technique was applied to the vein that receives blood from the coronary arteries. "With this approach, we are able to assess the blood supply to the heart muscle and assess how well the blood vessels of the heart function," he says.
Schwitter adds that finding early coronary flow problems could help protect the heart long before signs of calcification or obstruction develop. Patients with coronary artery disease risk factors -- such as high cholesterol, high blood pressure or diabetes, but who have no coronary artery disease -- are the most likely to benefit from the new preventive strategies that can now be assessed by using the PC-MR imaging technique.
The study of 16 healthy men between the ages of 22 and 32, and with no history of cardiovascular disease, compared the PC-MR technique with another type of imaging test called positron emission tomography (PET). A PET scan can provide physicians with information about the heart's blood supply and can also show the extent of damage to the heart. The testing was conducted at both the University of California at San Francisco and at the University Hospital of Zurich.
Although both the PC-MR and PET imaging techniques were equal in their ability to measure blood flow, PC-MR had the advantage of providing an excellent assessment of how the heart is working, Schwitter says. "This enhances our understanding of how blood flow to the heart muscle is controlled. This information is gained by the non-invasive PC-MR technique without requiring radiation and with lower costs," he says. However, the technique has some important limitations. "It can only show flow to the total heart muscle and offer a generalized view of the heart muscle," Schwitter adds.
Because researchers had information about both blood flow and heart function, they were able to obtain a more complete picture of how coronary circulation was functioning, says Schwitter. "Since functional disturbances of the vessels are thought to precede obstructions such as calcifications, we can focus on the earliest changes that are occurring during the development of coronary heart disease," he says.
The imaging tool is still experimental and is not designed for those who already have heart disease, Schwitter says. That's because there are more precise imaging techniques to pinpoint blockages in heart arteries, such as angiography.
Researchers say the technique may be "ideal" for studying blood flow abnormalities in other forms of heart disease, such as hypertension, valvular heart disease and cardiomyopathies.
Co-authors are T. DeMarco, M.D.; S. Kneifel, M.D.; G.K. von Schulthess, M.D., Ph.D.; M. Ciopor Jorg, M.D., Ph.D.; Hakan Arheden, M.D., Ph.D.; S. Ruhm, M.D.; K. Stumpe, M.D.; A. Buck, M.D.; W. W. Parmley, M.D.; T.F. Luscher, M.D. and C.B. Higgins, M.D.
Media Advisory: Dr. Schwitter can be reached at 41-1-255-1111. (Please do not publish numbers).