Assessing myocardial viability and infarct transmurality with left ventricular electromechanical mapping in patients with stable coronary artery disease: validation by delayed-enhancement magnetic resonance imaging.
BACKGROUND
This study was designed to define myocardial viability and establish practical cut-off values for differentiating normal myocardial tissue from subendocardial and transmural scar tissue by using electromechanical mapping (EMM). We validated our results by delayed-enhancement cardiac MRI (DE-MRI).


RESULTS
We prospectively studied 15 ambulatory patients with stable coronary disease who were candidates for cardiac catheterization. Within 48 hours of EMM, DE-MRI was performed. Using EMM software, we created a bull's eye precisely matched to that generated by DE-MRI. Segment by segment, we compared the MRI results to the corresponding unipolar voltage value for that same segment in the EMM bull's eye. Of 300 total segments, 275 were compared. The segments were divided into normal (n=211), subendocardial scar (n=49), and transmural scar (n=15). We found that subendocardial (6.8+/-2.9 mV) and transmural (4.6+/-1.9 mV) scar segments had significantly less unipolar voltage than normal (11.6+/-4.5 mV) segments (P<0.05 for each comparison). When normal myocardium was compared with myocardium with subendocardial scar, the threshold for differentiating between the two areas was 7.9 mV (sensitivity, 80%; specificity, 80%). Comparison of normal tissue to transmural scar yielded a threshold of 6.9 mV (sensitivity, 93%; specificity, 88%).


CONCLUSIONS
Our results demonstrate that normal myocardium can be accurately distinguished from myocardium with subendocardial or transmural infarcts on the basis of unipolar voltage values obtained through EMM. This is the first study to validate these results by using cardiac DE-MRI in humans.
Department of Adult Cardiology, Texas Heart Institute/St Luke's Episcopal Hospital and Baylor College of Medicine, Houston, Tex, USA. eperin@crescentb.net
Emerson C
EC
Perin
Guilherme V
GV
Silva
Rogerio
R
Sarmento-Leite
Andre L S
AL
Sousa
Marcus
M
Howell
Raja
R
Muthupillai
Brenda
B
Lambert
William K
WK
Vaughn
Scott D
SD
Flamm
D000328:Adult; D000368:Aged; D018780:Body Surface Potential Mapping / Q000379:methods*; D003324:Coronary Artery Disease / Q000175:diagnosis* / Q000503:physiopathology; D005260:Female; D006321:Heart / Q000503:physiopathology; D006352:Heart Ventricles; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000503:physiopathology; D012372:ROC Curve; D012016:Reference Values; D012680:Sensitivity and Specificity