Weaning failure can be caused by myocardial ischaemia during the switch from mechanical to spontaneous ventilation. We report ischaemic left ventricular failure and ischaemic mitral insufficiency during weaning. Angiography showed that the coronary vessels were stenosed. Transluminal angioplasty made weaning possible. We conclude that acute ischaemic mitral insufficiency may contribute to cardiac failure during weaning and that angioplasty, by reversing it, can allow successful weaning.