A 54-year-old gentleman presented with pulmonary oedema secondary to anterolateral papillary muscle (PPM) rupture and acute mitral regurgitation subsequent to myocardial ischaemia (MI). Angiography revealed complete occlusion of the first obtuse marginal (OM1) branch of the circumflex coronary artery and a 70% occlusion of the left anterior descending (LAD) coronary artery. Operatively, unusual anatomy was noted; an accessory head was attached superiorly to the anterior lateral PPM. This gave rise to chordae that were subsequently attached to the posterior second (P2) scallop. Additionally, the P2 scallop was deficient in chordae from the posteromedial PPM, thus, loss of this accessory head led to severe mitral regurgitation. We review the PPM anatomy and pathological context of PPM rupture and ischaemic mitral regurgitation.