We report a successful treatment of the complete papillary muscle rupture occurring 16 months after coronary artery bypass grafting (CABG). A 57-year-old man was admitted for the sudden onset of chest pain and cardiogenic shock. Emergency cardiac catheterization revealed severe mitral regurgitation and total occlusion in the right coronary artery, which was successfully revascularized by percutaneous coronary intervention under intra-aortic balloon pumping. The right internal thoracic artery grafted to the left anterior descending artery in the previous CABG was functioning well. An echocardiogram distinctly indicated the ruptured head of the papillary muscle. Since an emergency operation revealed complete rupture of the posterior papillary muscle, mitral valve replacement was carried out through an inverted L-shape sternotomy with T-shape left atriotomy. Our case indicates that the inverted L-shape sternotomy was a useful approach to preserve the function of grafts, and that T-shape left atriotomy offered a good exposure of the mitral valve in the limited surgical field.