Mitral valve replacement complications are more and more recognized due to the novel surgical techniques and the tendency to report such complications by young cardiologists and surgeons. Circumflex coronary artery injury is a rare complication that occurs during mitral valve replacement or repair by multiple mechanisms. We present the case of a 57-year-old female who underwent mitral valve replacement and ended up with heart failure after circumflex artery occlusion and failure of percutaneous coronary intervention.