Intraventricular dyssynchrony may play a role in the development of mitral regurgitation in dilated cardiomyopathy.
BACKGROUND
The development of functional mitral regurgitation (MR) in dilated cardiomyopathy (DCM) has been attributed to altered left ventricular (LV) geometry and annular dilatation. We propose the hypothesis that intraventricular dyssynchrony may play a role in the development of MR in DCM.


RESULTS
Tissue Doppler echocardiography was performed in 32 DCM patients to assess the time from the onset of the QRS complex to the peak systolic myocardial strain (Ts) at 2 segments adjacent to the anterolateral and posteromedial papillary muscles from a short axis view. The time difference corrected by the RR interval (DeltaTs/ radicalRR) was used to evaluate dyssynchrony of these segments. There was no difference in the QRS duration (103 +/- 29 ms versus 95 +/- 22 ms, P = .38) or the presence of left bundle branch block (39% versus 14 %, P = .25) between 18 patients with MR and 14 patients without MR. However, DeltaTs/ radicalRR was significantly increased in the patients with MR, compared with those without MR (104 +/- 67 ms versus 5 +/- 16 ms, P < .0001). Stepwise multiple regression analysis showed that DeltaTs/ radicalRR was independent contributing factor of MR.


CONCLUSIONS
Dyssynchrony of myocardial segments adjacent to the papillary muscles may disturb synchronized closure of the mitral leaflets and cause MR in DCM.
Soyama
Akiko
A
Third Division, Department of Internal Medicine, Osaka Medical College, Takatsuki-City, Osaka, Japan.
Kono
Tatsuji
T
Mishima
Takayuki
T
Morita
Hideaki
H
Ito
Takahide
T
Suwa
Michihiro
M
Kitaura
Yasushi
Y
D000328:Adult; D000368:Aged; D002311:Cardiomyopathy, Dilated / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*; D018618:Echocardiography, Doppler, Color; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008944:Mitral Valve Insufficiency / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology*; D009200:Myocardial Contraction; D010210:Papillary Muscles / Q000000981:diagnostic imaging / Q000503:physiopathology; D012044:Regression Analysis; D012720:Severity of Illness Index; D013318:Stroke Volume; D018487:Ventricular Dysfunction, Left / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*