By William Boggs, MD
NEW YORK, Oct 12 (Reuters Health) -- A new type of stress test using magnetic resonance imaging (MRI) is a safer and easier way to diagnose heart disease, says researchers.
Stress testing to detect impaired blood supply to the heart -- called ischemia -- is often problematic in patients who are obese, have severe lung disease, or have had previous cardiac surgery, according to Dr. W. Gregory Hundley and his associates at the Wake Forest University School of Medicine in Winston-Salem, North Carolina. Their report in the October 12th issue of Circulation: Journal of the American Heart Association suggests that the new technique may get around these problems.
"In the past, there was no suitable noninvasive stress testing for these patients," said Hundley in an interview with Reuters Health. "Now there is. We've shown that it's safe to do stress testing in the MR machine."
The investigators used a technique called fast cine MRI that allows observation of the changes in the heart muscle caused by ischemia induced by giving a drug, dobutamine, intravenously. Most of the patients tested were at least 20% overweight; 41% were more than 50% overweight. On average, the report indicates, fast cine MRI stress testing took 114 minutes, including preparation, testing, and recovery.
Among 139 patients tested, 36 had evidence of ischemia induced by the drug dobutamine, and 103 did not, the investigators report. When 41 of those patients subsequently underwent cardiac catheterization, the results confirmed the accuracy of fast cine MRI stress testing.
The researchers conclude that fast cine MRI testing accurately diagnoses inducible ischemia in these patients for whom other types of stress testing were not possible.
"In fact," Hundley said, "MRI stress testing should also be suitable for just about everyone else. The main limitation is whether they can fit into the MRI machine."
"We may soon be able to sort out multiple issues in a patient at one time, using this technology," Hundley continued. He said that software developed at Wake Forest is being incorporated into existing MRI equipment so that such procedures could be possible throughout the US within the next year.
"The future of MRI is no longer just over the horizon," comment Drs. Gerald Pohost and Robert Biederman from the University of Alabama at Birmingham, in a related editorial. "This insightful work by Hundley et al. adds to the accumulating body of literature demonstrating the present ability and certain potential of a technology that will be the cornerstone for cardiovascular imaging in the next millennium."
