Acute effects of cardiac resynchronization therapy on functional mitral regurgitation in advanced systolic heart failure.
OBJECTIVE
We studied the acute effects of cardiac resynchronization therapy (CRT) on functional mitral regurgitation in heart failure (HF) patients with left bundle branch block (LBBB).


BACKGROUND
Both an decrease [corrected] in left ventricular (LV) closing force and mitral valve tethering have been implicated as mechanisms for functional mitral regurgitation (FMR) in dilated hearts. We hypothesized that an increase in LV closing force achieved by CRT could act to reduce FMR.


METHODS
Twenty-four HF patients with LBBB and FMR were studied after implantation of a biventricular CRT system. Acute changes in FMR severity between intrinsic conduction (OFF) and CRT were quantified according to the proximal isovelocity surface area method by measuring the effective regurgitant orifice area (EROA). Results were compared with the changes in estimated maximal rate of left ventricular systolic pressure rise (LV+dP/dt(max)) and transmitral pressure gradients (TMP), both measured by Doppler echocardiography.


RESULTS
Cardiac resynchronization therapy was associated with a significant reduction in FMR severity. Effective regurgitant orifice area decreased from 25 +/- 19 mm(2) (OFF) to 13 +/- 8 mm(2) (CRT). The change in EROA was directly related to the increase in LV+dP/dt(max) (r = -0.83, p < 0.0001). Compared with OFF, TMP increased more rapidly during CRT, and a higher maximal TMP was observed (OFF 73 +/- 24 mm Hg vs. CRT 85 +/- 26 mm Hg, p < 0.01).


CONCLUSIONS
Functional mitral regurgitation is reduced by CRT in patients with HF and LBBB. This effect is directly related to the increased closing force (LV+dP/dt(max)). The results support the hypothesis that an increase in TMP, mediated by a rise in LV+dP/dt(max) due to more coordinated LV contraction, may facilitate effective mitral valve closure.
Breithardt
Ole A
OA
Department of Cardiology, University Hospital, Aachen, Germany. olebreithardt@gmx.de
Sinha
Anil M
AM
Schwammenthal
Ehud
E
Bidaoui
Nadim
N
Markus
Kai U
KU
Franke
Andreas
A
Stellbrink
Christoph
C
D000368:Aged; D002037:Bundle-Branch Block / Q000150:complications / Q000000981:diagnostic imaging* / Q000628:therapy*; D002304:Cardiac Pacing, Artificial; D002311:Cardiomyopathy, Dilated / Q000150:complications / Q000000981:diagnostic imaging* / Q000628:therapy*; D015331:Cohort Studies; D004452:Echocardiography; D015150:Echocardiography, Doppler; D005260:Female; D005500:Follow-Up Studies; D006334:Heart Function Tests; D006801:Humans; D008297:Male; D008875:Middle Aged; D008944:Mitral Valve Insufficiency / Q000150:complications / Q000000981:diagnostic imaging* / Q000628:therapy*; D015588:Observer Variation; D011336:Probability; D011446:Prospective Studies; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D013318:Stroke Volume; D016896:Treatment Outcome