Non¿pharmacological treatment of refractory angina: The coronary sinus reducer, the new kid on the block Sérgio Madeira; Catarina Brízido; Luís Raposo; João Brito; Nélson Vale; Sílvio Leal; Pedro de Araújo Gonçalves; Henrique Mesquita Gabriel; Rui Campante Teles; Manuel Almeida;