​Ischemic or idiopathic mitral valve disease (so called secondary mitral valve regurgitation) is a rather new concept. This topic is deeply polarizing the attention of the cardiologist and cardiothoracic community. Although there is an impressive amount of efforts to understand the etiology, mechanism, treatment and prognostic factors, still clear indications and guide-lines are missing. Therefore this group of patients lie in a grey-area and physicians looking after them cannot count on proper recommendations. The main purpose of this book is to review the most relevant knowledge about secondary mitral valve regurgitation, from the anatomy, definition, classification, diagnosis and prevalence to the up-to-date surgical and medical management.