Abstract 3680: Mechanism of Beneficial Effects of Restrictive Mitral Annuloplasty on Left Ventricular Contractile State in Patients With Dilated Cardiomyopathy and Functional Mitral Regurgitation
Background. Although recent studies indicate the efficacy of restrictive mitral annuloplasty (RMA) in patients with dilated cardiomyopathy and functional mitral regurgitation, the mechanisms responsible for favorable effects on left ventricular (LV) ejection performance has been poorly understood. We investigated global and regional ejection performance before and after RMA using multidetector computed tomographic (MDCT) images and our newly developed software system.
Methods. Twenty-four dilated cardiomyopathy patients with more than mild functional mitral regurgitation underwent stringent downsizing annuloplasty with a semi-rigid complete ring (24 or 26mm). MDCT angiography was performed before and 2 months after RMA. For image analysis, LV long-axis and short-axis images were reconstructed throughout one cardiac cycle. Software automatically calculated end-diastolic (EDV) and end-systolic volume (ESV), ejection fraction, meridional (ESSm) and circumferential end-systolic wall stress (ESSc) according to AHA LV segment model.
Results. LVEDV and LVESV decreased from 240+/−55 to 202+/−59 ml (p=0.002) and from 186+/−79 to 138+/−67 ml (p=0.01), respectively. LV ejection fraction improved from 27+/−8.7 to 36+/−14% (p=0.001). Regional ESSm significantly decreased at the basal (193+/−56 to 169+/−66, p=.004), mid (196+/−59 to 162+/−64, p=.0006), and apical portion (176+/−59 to 145+/−59, p=0.0002) and cross-sectional ejection fraction improved at each region. Global ESSc decreased from 189+/−56 to 159+/−62 kdynes/cm2 (p<0.001). There were significant correlations between change in LVEDV and LVESV (r=0.77, p<.001), and change in LVESV and ESSc (r=0.60, p=0.003). Moreover, the magnitude of increase in LV ejection fraction significantly correlated with the degree of decrease in ESSc (r=−0.61, p=0.002).
Conclusion; In patients with dilated cardiomyopathy and functional mitral regurgitation, RMA resulted in a smaller LV size, allowing a reduced regional and global end-systolic stress. Our study indicated that the reduction of afterload was partly responsible for postoperative improvement in LV ejection performance after RMA.