Abstract 2702: Progressive Loss of Miral Annular Saddle Shape Occurs as Chronic Ischemic Mitral Regurgitation Develops
Background: The normal mitral annulus of all studied species has been demonstrated to have a distinct saddle shape. Studies utilizing sonomicrometry array localization have demonstrated that annular flattening occurs early after posterior infarctions (MI) associated with acute ischemic mitral regurgitation (IMR). An association between progressive annular flattening (i.e. loss of saddle shape) has not been established. Finite element analysis has suggested that even a modest decrement in annular non-planarity produces a dramatic increase in peak leaflet stress. Therefore, mitral annular non-planarity (saddling) may represent a useful diagnostic and therapeutic target in patients with IMR. We used real-time three-dimensional echocardiography (rt-3DE), a non invasive, clinically applicable imaging modality, to assess the changes in ovine mitral annular geometry before, immediately after and 8 weeks after a posterior MI that reliably results in moderate to severe chronic IMR.
Methods: Rt-3DE images were acquired using a Phillips Sonos 7500 platform in six sheep prior to, immediately after and 8 weeks after posterior MI. Off-line analyses were performed with Tomtec 4D Cardio-View software and proprietary analytical software.
Results: Values are presented as the mean ± standard deviation. Mitral annular height (AH) decreased by 28 % and 39 % with respect to baseline immediately after infarction and at 8 week follow-up. Inter-commissural width (CW) increased by 11 % and 28 %. The annular height to commissural width ratio (AHCWR), a measure of annular “saddleness” decreased by 35 % and 53 % respectively. Mitral annular area (MAA) increased by 13 % and 44 %, respectively. All animals had 3+ IMR at the 8 week follow-up
Conclusion: There is a progressive loss of mitral annular saddle shape after posterior MI that results in IMR. Restoration of the normal saddle shape may improve results of repair operations for IMR. More laboratory and clinical studies are necessary.