The Hopkins development, if confirmed in further pathology studies in humans, could standardize how physicians currently gauge the severity of a heart attack and a patient's chances for recovery. A variety of methods are currently used to determine the size of an infarct by MRI, such as visual cues, but these estimates have been shown in previous studies to overestimate damage by an average of 11 percent.

The researchers, whose findings will be published in the Journal of the American College of Cardiology online Dec. 21, hope to apply this information for determining more accurate dosing regimens for stem cell therapies currently under development, in which upwards of 200 million stem cells are injected directly into the damaged heart muscle.

"The size of a heart attack matters for determining how well a patient will recover from the trauma. Current methods for measuring the size of an infarct and assessing how much damage was done are highly subjective and arbitrary," said senior study author and cardiologist Joo Lima, M.D., associate professor of medicine and radiology at The Johns Hopkins University School of Medicine and its Heart Institute. "Indeed, a person who has suffered damage to more than 30 percent of the left ventricle of the heart is twice as likely to die within a year from the injury than someone who has suffered less damage, and bigger infarcts often require more aggressive drug therapy or, in the most severe cases, surgery to repair heart tissue or prevent further damage."

The Hopkins team measured the size of an m.i. in 13 dogs using eight different methods for analyzing pictures taken by a standard MRI, ranging from visual cues to v
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Contact: David March
dmarch1@jhmi.edu
410-955-1534
Johns Hopkins Medical Institutions
20-Dec-2004