Abstract Mycobacterium chimaera infections have been associated with contamination of a heater–cooler unit used during cardiopulmonary bypass procedures since 2006. Mycobacterium chimaera is a slow-growing non-tuberculous mycobacterium responsible for an infection, which is difficult to treat and has often a devastating course. Until now, M. chimaera infection has been shown to occur up to 8 years after operation. We report a patient presenting with an aortic pseudoaneurysm who developed M. chimaera infection 12 years after repair of an acute type A aortic dissection with graft replacement of the ascending aorta and stent-grafting of the arch. As far as we know, this is the case with the longest incubation period of M. chimaera infection. The present experience indicates that all patients who underwent open heart procedures since 2006 with such heater–cooler unit model should be closely followed up regardless of time of index surgery.