Response of functional mitral regurgitation during dobutamine infusion in relation to changes in left ventricular dyssynchrony and mitral valve geometry.
OBJECTIVE
Functional mitral regurgitation (FMR) and myocardial dyssynchrony commonly occur in patients with dilated cardiomyopathy (DCM). The aim of this study was to elucidate changes in FMR in relation to those in left ventricular (LV) dyssynchrony as well as geometric parameters of the mitral valve (MV) in DCM patients during dobutamine infusion.


METHODS
Twenty-nine DCM patients (M:F=15:14; age: 62±15 yrs) with FMR underwent echocardiography at baseline and during peak dose (30 or 40 ug/min) of dobutamine infusion. Using 2D echocardiography, LV end-diastolic volume, end-systolic volume (LVESV), ejection fraction (EF), and effective regurgitant orifice area (ERO) were estimated. Dyssynchrony indices (DIs), defined as the standard deviation of time interval-to-peak myocardial systolic contraction of eight LV segments, were measured. Using the multi-planar reconstructive mode from commercially available 3D image analysis software, MV tenting area (MVTa) was measured. All geometrical measurements were corrected (c) by the height of each patient.


RESULTS
During dobutamine infusion, EF (28±8% vs. 39±11%, p=0.001) improved along with significant decrease in cLVESV (80.1±35.2 mm³/m vs. 60.4±31.1 mm³/m, p=0.001); cMVTa (1.28±0.48 cm²/m vs. 0.79±0.33 cm²/m, p=0.001) was significantly reduced; and DI (1.31±0.51 vs. 1.58±0.68, p=0.025) showed significant increase. Despite significant deterioration of LV dyssynchrony during dobutamine infusion, ERO (0.16±0.09 cm² vs. 0.09±0.08 cm², p=0.001) significantly improved. On multivariate analysis, ΔcMVTa and ΔEF were found to be the strongest independent determinants of ΔERO (R²=0.443, p=0.001).


CONCLUSIONS
Rather than LV dyssynchrony, MV geometry determined by LV geometry and systolic pressure, which represents the MV closing force, may be the primary determinant of MR severity.
Division of Cardiology, Department of Internal Medicine, Konkuk University College of Medicine, Chungju, Korea.
Woong Gil
WG
Choi
Division of Cardiology, Department of Internal Medicine, Konkuk University College of Medicine, Chungju, Korea.
Soo Hyun
SH
Kim
Division of Cardiology, Department of Internal Medicine, Inha University College of Medicine, Incheon, Korea.
Soo Han
SH
Kim
Division of Cardiology, Department of Internal Medicine, Inha University College of Medicine, Incheon, Korea.
Sang Don
SD
Park
Division of Cardiology, Department of Internal Medicine, Inha University College of Medicine, Incheon, Korea.
Young Soo
YS
Baek
Division of Cardiology, Department of Internal Medicine, Inha University College of Medicine, Incheon, Korea.
Sung Hee
SH
Shin
Division of Cardiology, Department of Internal Medicine, Inha University College of Medicine, Incheon, Korea.
Sung Il
SI
Woo
Division of Cardiology, Department of Internal Medicine, Inha University College of Medicine, Incheon, Korea.
Dae Hyeok
DH
Kim
Division of Cardiology, Department of Internal Medicine, Inha University College of Medicine, Incheon, Korea.
Keum Soo
KS
Park
Division of Cardiology, Department of Internal Medicine, Inha University College of Medicine, Incheon, Korea.
Jun
J
Kwan
D000368:Aged; D004280:Dobutamine / Q000008:administration & dosage / Q000494:pharmacology*; D004452:Echocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve / Q000033:anatomy & histology* / Q000187:drug effects / Q000503:physiopathology*; D008944:Mitral Valve Insufficiency / Q000503:physiopathology*; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology*
D004280:Dobutamine
Mitral regurgitation; dobutamine; dyssynchrony