Conventional mitral valve surgery (either repair or replacement) is the standard of care for patients with severe symptomatic mitral valve (MV) regurgitation or stenosis. Although a substantial portion of these patients are not eligible for surgery because of comorbidity and a high surgical risk [
1]. Transcatheter mitral valve replacement (TMVR) and repair (TMVr) are enticing, but slowly evolving therapeutic options for patients with MV disease, in particular for those with a high surgical risk and those not eligible for an open procedure. Edge-to-edge leaflet repair with the MitraClip (Abbott, Chicago, IL) is the only TMVr system with the most experience to date. However, not all MV pathologies are suitable for this technique and residual moderate to severe mitral regurgitation (MR) has been reported in approximately 10% of the patients [
2,
3]. For the treatment of severe MR, TMVR has emerged as an alternative. Although transcatheter aortic valve replacement (TAVR) is a well-established treatment option for patients with severe aortic stenosis, the experience with TMVR remains limited [
4]. Some experience has been gained with the off-label use of TAVR devices for “valve-in-ring” remedial procedures for failed mitral valve repair [
5‐
7], but the development of dedicated TMVR valves is currently still in its infancy [
8‐
10]. The complexity of MV anatomy, its proximity to the left ventricular outflow tract (LVOT) and the hemodynamic forces a TMVR device must anchor and function under, have generated significant design challenges. Potential complications of TMVR are LVOT obstruction, device embolization, left ventricular dysfunction (e.g. chordae tendineae rupture) and death [
11]
. Despite these technical, anatomical, and functional constraints, substantial progress has been made over the last several years. The majority of TMVR devices currently being developed use a varying combination of annular interference fit, leaflet grasping or apical fixation as anchoring strategies. Left atrial anchoring strategies have been proposed, but less well explored.
The recently introduced supra-annular AltaValve (4C Medical Technologies, Brooklyn Park, Minnesota) is based on a LA anchoring mechanism and directly addresses MR without replacing the native mitral valve or disrupting the mitral annulus and leaflets, subvalvular apparatus, LVOT or aortic valve [
12].
Though relatively unexplored the LA anchoring mechanism may prove a very efficient design option for development of TMVR devices. Further development of this anchoring strategy will require feasibility and efficacy studies in normal and ischemic MR (IMR) animal models. To carry out these studies animal prototypes will need to be created based on LA size and geometry. This information is not currently available in the literature. Therefore, we sought to describe LA systolic and diastolic geometry in both normal sheep and an ovine IMR model using magnetic resonance imaging (MRI) and echocardiography. This data will facilitate future research focusing on TMVR device development for (I)MR with LA anchoring mechanisms.