"Not only have we found thinned areas that could be saved by revascularization, we have learned some new concepts that will allow us to predict which of the thinned areas could be saved," said cardiologist Raymond Kim, M.D., co-director of the Duke Cardiovascular Magnetic Resonance Center and member of the research team. "It appears to depend on the ratio of viable cells to scar tissue in the thinned area and not just the absolute amount of viable cells.
"This is important since most other viability tests measure only the amount of viable tissue and not the amount of scar," Kim continued. "Thus, thinned areas will generally be interpreted as dead because the amount of viable tissue is small by definition."
When a portion of heart muscle is deprived of blood flow, as in a heart attack, those muscle cells are deprived of needed oxygen and nutrients. As the muscle cells in the walls of the heart die, they are replaced by collagen, which makes the walls thinner and less effective in pumping.
For their study, the Duke team evaluated 30 patients with chronic coronary artery disease who had large areas of thinned myocardium, or heart muscle. Each patient received an initial MRI scan to determine myocardial viability, and then another after having a revascularization procedure.
Patients were then divided into two groups - 19 who had less than 50 percent viability before revascularization, and 11 who had greater than 50 percent.
"After revascularization, the patients in the first group demonstrated minimal functional improvement in the thinned region, while the second group had significant improvement not only in contractile function but also wall thickness," Shah said.
Specifically, the group with greater than 50 percent alive-to-dead cells experienced an increase in diastolic wall thick
Contact: Richard Merritt
Duke University Medical Center