Differentiation of subendocardial and transmural infarction using two-dimensional strain rate imaging to assess short-axis and long-axis myocardial function.
OBJECTIVE
This study sought to differentiate the transmural extent of infarction (TME) by assessment of the short-axis and long-axis function of the left ventricle (LV) using 2-dimensional (2D) strain.


BACKGROUND
The differentiation of subendocardial infarction from transmural infarction has significant prognostic and clinical implications.


METHODS
Contrast-enhanced magnetic resonance imaging (CE-MRI) and dobutamine stress echocardiography (DBE) were performed in 80 patients (age 63 +/- 10 years) with chronic ischemic LV dysfunction. Myocardial function was assessed in the short axis at the midventricular level using peak strain rate (SR) and strain (S) in circumferential and radial dimensions, and was assessed in the long axis using longitudinal SR and S. Wall motion analysis was performed during DBE to assess for contractile reserve.


RESULTS
Transmural infarct segments had lower circumferential S (-10.7 +/- 6.3) and SR (-1.0 +/- 0.4) than subendocardial infarcts (S: -15.4 +/- 7.0, p < 0.0001; SR: -1.4 +/- 0.8, p = 0.02) and normal myocardium (S: p < 0.0001; SR: p < 0.0001). Transmural and subendocardial infarct segments had similar radial S and SR. Subendocardial infarct segments showed significant reduction of longitudinal S (-13.2 +/- 5.6) and SR (-0.91 +/- 0.45) compared with normal myocardium (S: -17.8 +/- 5.4, p < 0.0001; SR: -1.1 +/- 0.41, p < 0.0001), but there were no significant differences between subendocardial and transmural infarct segments (p = 0.09). Wall motion analysis by DBE could not identify subendocardial infarction on CE-MRI (TME 1% to 50%: DBE scar 38%, DBE viable 38%, DBE ischemic 24%, p = NS).


CONCLUSIONS
The combined assessment of long-axis and short-axis function using 2D strain may be used to identify TME.
Chan
Jonathan
J
University of Queensland, Brisbane, Australia.
Hanekom
Lizelle
L
Wong
Chiew
C
Leano
Rodel
R
Cho
Goo-Yeong
GY
Marwick
Thomas H
TH
D000368:Aged; D003287:Contrast Media; D003937:Diagnosis, Differential; D004452:Echocardiography; D025401:Echocardiography, Stress; D005240:Feasibility Studies; D005260:Female; D006321:Heart / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000145:classification* / Q000175:diagnosis* / Q000503:physiopathology; D015203:Reproducibility of Results
D003287:Contrast Media