Mechanical dyssynchrony or myocardial shortening as MRI predictor of response to biventricular pacing?
OBJECTIVE
To investigate whether mechanical dyssynchrony (regional timing differences) or heterogeneity (regional strain differences) in myocardial function should be used to predict the response to cardiac resynchronization therapy (CRT).


METHODS
Baseline mechanical function was studied with MRI in 29 patients with chronic heart failure. Using myocardial tagging, two mechanical dyssynchrony parameters were defined: the standard deviation (SD) in onset time (T onset) and in time to first peak (T peak,first) of circumferential shortening. Electrical dyssynchrony was described by QRS width. Further, two heterogeneity parameters were defined: the coefficient of variation (CV) in end-systolic strain and the difference between peak septal and lateral strain (DiffSLpeakCS). The relative increase in maximum rate of left ventricle pressure rise (dP/dt max) quantified the acute response to CRT.


RESULTS
The heterogeneity parameters correlated better with acute response (CV: r = 0.58, DiffSLpeakCS: r = 0.63, P < 0.005) than the mechanical dyssynchrony parameters (SD(T onset): r = 0.36, SD(T peak,first) r = 0.47, P = 0.01, but similar to electrical dyssynchrony (r = 0.62, P < 0.001). When a heterogeneity parameter was combined with electrical dyssynchrony, the correlation increased (r > 0.70, P incr < 0.05).


CONCLUSIONS
Regional heterogeneity in myocardial shortening correlates better with response to CRT than mechanical dyssynchrony, but should be combined with electrical dyssynchrony to improve prediction of response beyond the prediction from electrical dyssynchrony only.
Rüssel
Iris K
IK
Department of Physics and Medical Technology, VU University Medical Center, Amsterdam, The Netherlands.
Zwanenburg
Jaco J M
JJ
Germans
Tjeerd
T
Marcus
J Tim
JT
Allaart
Cornelis P
CP
de Cock
Carel C
CC
Götte
Marco J W
MJ
van Rossum
Albert C
AC
D000368:Aged; D002304:Cardiac Pacing, Artificial; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006333:Heart Failure / Q000503:physiopathology* / Q000628:therapy*; D006801:Humans; D016014:Linear Models; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D017202:Myocardial Ischemia / Q000175:diagnosis* / Q000503:physiopathology*; D011237:Predictive Value of Tests
D003287:Contrast Media; D019786:Gadolinium DTPA