This study is an Expanded Access Program that focuses on individuals who have transthyretin amyloidosis with cardiomyopathy (ATTR amyloidosis with cardiomyopathy). Expanded Access Programs are a means by which investigational treatments are made available to treat patients with serious diseases who are unable to participate in an ongoing clinical trial or whose treatment options are otherwise limited. In this study, an experimental drug called patisiran is being offered for the treatment of ATTR amyloidosis with cardiomyopathy. (Patisiran is an approved therapy in the U.S. for the treatment of hereditary ATTR amyloidosis with polyneuropathy.) ATTR amyloidosis is a rare and serious disease that affects multiple systems of the body, including the heart. It is caused by certain differences in a protein called transthyretin (TTR). Patisiran blocks the ability of ribonucleic acid (RNA) to produce normal and abnormal forms of the TTR protein. This decrease in production is expected to lower TTR levels in the blood and reduce the progression of amyloid build up in organs of patients with ATTR amyloidosis. Amyloid accumulation can often compromise the function of important organs.