A prosthetic mitral valve includes a collapsible and expandable stent extending from an inflow end to an outflow end. A collapsible and expandable valve assembly is disposed within the stent. The valve assembly includes a plurality of anterior leaflets and one posterior leaflet. The posterior leaflet has a larger surface area than any of the anterior leaflets. When implanted in the native mitral valve annulus, the smaller size of the anterior leaflets and the corresponding smaller size of an anterior portion of the stent reduce the likelihood of interference with blood flowing through the native aortic valve, while also reducing the likelihood of ventricular fibrillation.