APOLLO is an open-label, multicenter, randomized trial enrolling 1600 patients with moderate to severe or severe symptomatic mitral regurgitation. Surgical candidates are randomized in 1:1 fashion, to transcatheter mitral valve replacement (TMVR, self-expanding nitinol valve with bovine pericardial leaflets delivered via transapical or transseptal approach using the Intrepid system, Medtronic Inc., Redwood City, CA) vs surgical mitral valve replacement (SMVR). Non-surgical candidates will receive TMVR. Estimated primary completion: October 2021. Primary composite outcome includes 1-year all-cause mortality, disabling stroke, reoperation or reintervention and cardiovascular hospitalization. Early experience with the Intrepid system from the transapical approach, among 50 consecutive patients at high or extreme risk for SMVR was successful in 48/50 patients and 30-day mortality was 14%.