This case describes a patient who underwent mitral valve replacement (MVR) surgery with preservation of the subvalvular apparatus who suffered anterolateral papillary muscle rupture (PMR) postseparation from cardiopulmonary bypass. This patient had no history of coronary artery disease (CAD); subsequent pathology of the papillary muscle showed evidence of amyloid deposition. Although most PMRs are caused by ischemia from CAD, cardiac amyloidosis must be considered in the absence of CAD and worked up appropriately as cardiac involvement of amyloidosis, especially the amyloid light-chain (AL) subtype, is prognostic of increased mortality that can be mitigated with therapy.