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MRI USED TO ASSESS DAMAGE, PREDICT RECOVERY AFTER HEART ATTACKA physician caring for a patient who has suffered a heart attack would like to be able to tell the patient to what extent the heart muscle is damaged and how much the muscle is likely to recover. A study in the Nov. 15 issue of the Journal of the American College of Cardiology found that use of magnetic resonance imaging (MRI) to assess the heart muscle might make that easier.“There are two factors that determine recovery of heart muscle after a heart attack - the extent of damage to the small blood vessels in the heart and the amount of functional reserve the muscle has. Most diagnostic tests in cardiology can assess one or the other of these but not both. Use of MRI, a new technique for imaging the heart, may mean that we only need one non-invasive test to assess damage and measure blood flow,” said Dr. Christopher M. Kramer, associate professor of radiology and internal medicine at the University of Virginia Health System in Charlottesville and lead investigator for the study. Kramer and his colleagues studied 23 patients who experienced a first heart attack and had blood flow restored to the previously blocked artery. An MRI was performed on these patients three days after the heart attack using two assessment techniques. To measure blood flow in the heart, researchers injected a standard MRI contrast agent, Gd-DTPA or Gadolinium. They determined how much of the contrast agent got to the heart muscle initially and how much remained there after five minutes. To measure the functional reserve of the heart muscle, researchers infused an agent known to stimulate the heart, called dobutamine, and assessed the response. The patients returned for a repeat MRI two months after the heart attack. The investigators concluded that, together, the two assessments could help predict the likelihood of recovery of heart function. The patterns of uptake of the contrast agent predicted how much damage had occurred to the muscle and to what extent recovery would take place after two months. The response to dobutamine in the heart during the first MRI also predicted how well the muscle would function during the second MRI. “In this study, we saw that a single cardiac MRI can assess two properties of heart muscle. For physicians, it would be useful to evaluate these properties of heart muscle in one test, both after a heart attack and in patients who might be candidates for procedures such as angioplasty or bypass surgery. We are excited about this potential, and further research is ongoing at U.Va. to evaluate these and other uses of cardiac MRI,” Kramer said. November 14, 2000 |