A replacement heart valve commissure assembly may include: a locking mechanism including a first locking portion spaced apart from a second locking portion in a delivery configuration and configured to engage the second locking portion in a deployed configuration, the first locking portion being longitudinally actuatable relative to the second locking portion between the delivery and deployed configurations; and first and second valve leaflets secured to the first locking portion. A first sleeve portion of the first valve leaflet may be fixedly attached to a first fabric sleeve wrapped around a first leg of the first locking portion. A second sleeve portion of the second valve leaflet may be fixedly attached to a second fabric sleeve wrapped around a second leg of the first locking portion. The first fabric sleeve may include first and second end portions, and an elastic central portion configured to engage the first leg.