 1. A multicenter registry of UCA patients, their family members and referred patients with familial sudden death undergoing standardized testing for evidence of primary electrical disease PED. The single center pilot experience at the applicants institution has proven feasibility, and has been accepted for publication in Circulation, indicating novelty. Ten centers across Canada have agreed to participate. The target is to enroll 1500 UCA probands, 1st degree family members. 1st degree relatives of autopsy negative unexplained sudden death victims. 