Background: Little is known about the last phase of life of patients with implantable cardioverter defibrillators and the practice of advance care planning in this population. Aim: To describe the last phase of life and advance care planning process of patients with an implantable cardioverter defibrillator, and to assess relatives' satisfaction with treatment and care. Design: Mixed-methods study, including a survey and focus group study. Setting/participants: A survey among 170 relatives (response rate 59%) reporting about 154 deceased patients, and 5 subsequent focus groups with 23 relatives. Results: Relatives reported that 38% of patients had a conversation with a healthcare professional about implantable cardioverter defibrillator deactivation. Patients' and relatives' lack of knowledge about device functioning and the perceived lack of time of healthcare professionals were frequently mentioned barriers to advance care planning. Twenty-four percent of patients experienced a shock in the last month of life, which were, according to relatives, distressing for 74% of patients and 73% of relatives. Forty-two to sixty-one percent of relatives reported to be satisfied with different aspects of end-of-life care, such as the way in which wishes of the patient were respected. Quality of death was scored higher for patients with a deactivated device than those with an active device (6.74 vs 5.67 on a 10-point scale, p = 0.012). Conclusions: Implantable cardioverter defibrillator deactivation was discussed with a minority of patients. Device shocks were reported to be distressing to patients and relatives. Relatives of patients with a deactivated device reported a higher quality of death compared to relatives of patients with an active device.