Early assessment of myocardial salvage by contrast-enhanced magnetic resonance imaging.
BACKGROUND
Myocardial salvage after acute myocardial infarction is defined clinically by early restoration of flow and long-term improvement in contractile function. We hypothesized that contrast-enhanced magnetic resonance imaging (MRI), performed early after myocardial infarction, indexes myocardial salvage. We studied the relationship between the transmural extent of hyperenhancement by contrast-enhanced MRI, restoration of flow, and recovery of function.


RESULTS
The left anterior descending coronary artery was occluded in dogs (n=15) for either 45 minutes, 90 minutes, or permanently. Cine and contrast-enhanced MRI were performed 3 days after the procedure; cine MRI was also done 10 and 28 days after the procedure. The transmural extent of hyperenhancement and wall thickening were determined using a 60-segment model. The mean transmural extent of hyperenhancement for the 45-minute occlusion group was 22% of the 90-minute group and 18% of the permanent occlusion group (P:<0.05 for both). The transmural extent of hyperenhancement on day 3 was related to future improvement in both wall thickening score and absolute wall thickening at 10 and 28 days (P:<0.0001 for each). For example, of the 415 segments on day 3 that were dysfunctional and had <25% transmural hyperenhancement, 362 (87%) improved by day 28. Conversely, no segments (0 of 9) with 100% hyperenhancement improved. The transmural extent of hyperenhancement on day 3 was a better predictor of improvement in contractile function than occlusion time (P:<0.0001).


CONCLUSIONS
A reduction in the transmural extent of hyperenhancement by contrast-enhanced MRI early after myocardial infarction is associated with an early restoration of flow and future improvement in contractile function.
Hillenbrand
H B
HB
Northwestern University Medical School Feinberg Cardiovascular Research Institute, Chicago, IL 60611-3008, USA.
Kim
R J
RJ
Parker
M A
MA
Fieno
D S
DS
Judd
R M
RM
D000208:Acute Disease; D000818:Animals; D003287:Contrast Media; D003326:Coronary Circulation; D004285:Dogs; D007089:Image Enhancement; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009203:Myocardial Infarction / Q000175:diagnosis*; D011237:Predictive Value of Tests
D003287:Contrast Media