Methods, devices, and systems are provided for performing endovascular repair of atrioventricular and other cardiac valves in the heart. A delivery device for staged deployment of an implantable device to a target area. The delivery device includes a deployment handle and one or more lock lines extending from the deployment handle through the catheter to the implantable device, the one or more lock lines being configured to engage with the implantable device to allow locking of the implantable device.