Concordance between mechanical and electrical dyssynchrony in heart failure patients: a function of the underlying cardiomyopathy?
BACKGROUND
Cardiac resynchronization therapy (CRT) improves heart failure (HF) symptoms through a reduction of cardiac mechanical dyssynchrony. Mechanical dyssynchrony is currently estimated by electrical dyssynchrony (QRS duration). It is known that electrical and mechanical dyssynchrony are not well correlated in HF patients. However, there is limited information about whether this relationship might be influenced by the underlying cardiomyopathy.


METHODS
Doppler echocardiography was performed in 88 patients presenting with heart failure due to ischemic (n = 42) or nonischemic (n = 46) heart disease, left ventricular ejection fraction <40%, New York Heart Association class II-IV, regardless of their QRS duration. Interventricular dyssynchrony was assessed by the time interval between preaortic and prepulmonary ejection times. Intraventricular dyssynchrony was ascertained by (1) the delay between the earliest and the latest peak negative longitudinal strain recorded in the basal and mid-segments of the lateral and septal walls (TMinMax) and (2) the standard deviation of time-to-peak in the same segments (SDdys).


RESULTS
The correlation coefficient between QRS duration and mechanical interventricular dyssynchrony was r = 0.47 (P < 0.001) in patients with nonischemic disease and nonsignificant in patients with ischemic disease. Similarly, the correlation coefficient between QRS duration and mechanical intraventricular dyssynchrony was significant in patients with nonischemic disease (r = 0.37, P = 0.01 for TMinMax; r = 0.42, P = 0.003 for SDdys) and nonsignificant in patients with ischemic disease.


CONCLUSIONS
The concordance between electrical dyssynchrony assessed by QRS duration and mechanical dyssynchrony assessed by myocardial strain is dependent upon the underlying cardiomyopathy. This observation may improve our understanding of the various responses observed in CRT patients.
Department of Cardiology, Rennes University Hospital, France.
François
F
Tournoux
Erwan
E
Donal
Christophe
C
Leclercq
Christian
C
De Place
Christophe
C
Crocq
Aude
A
Solnon
Alain
A
Cohen-Solal
Philippe
P
Mabo
Jean-Claude
JC
Daubert
D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D002304:Cardiac Pacing, Artificial / Q000379:methods; D015150:Echocardiography, Doppler / Q000379:methods; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy; D008875:Middle Aged