L1A Visa Stamp in Canada having USA Approved L1A Petition & I-94

Hello,–I am working in USA on L1A Visa, My Visa got expire and some time before I applied for Extention, I got the extention and recieved the Approved Petition and I-94 Extended.I want to travel to Niagra/Toronto for a Trip. In this case how I can get my VISA Stamp in Canad? What kind of document I need to carry? Is there any risk to visit in this case(having approved Petition and valid I-94 but not having Visa Stamped). what is the Success Rate in such cases. Appreciate your help