The APOLLO-B trial randomized patients with ATTRv- CM or ATTRwt- CM and a history of HF (but current clinically stable), NT- proBNP levels ranging from 300 ng/L to 8,500 ng/L and a 6MWD of ≥150 m to patisiran or placebo. The gene discussed is NPPB; the disease is hydrops fetalis.