Although ICDs are effective in preventing sudden cardiac death, they can also profoundly affect patients' and partner/caregivers' emotional well-being, social relationships, and daily functioning. Previous phases of the QoL-ICD project used patient-reported outcome measures (PROMs) and support group discussions to identify key domains affecting quality of life: patient education, physical health, psychological and social well-being, and end-of-life awareness. However, these methods have limitations in capturing the full depth and context of lived experience.

To complement and expand on these findings, this study uses in-depth, semi-structured interviews to explore how ICD patients and their partners interpret and navigate these challenges in their own words. Interviews provide a richer understanding of personal experiences, unmet needs, and barriers to care that are not easily measurable through questionnaires alone. Including both patients and their partners offers insight into relational dynamics and caregiving perspectives.

The primary objective of this study is to explore the lived experiences of ICD patients and their partners across four key domains:

• Patient education and information provision
• Physical health and activity
• Psychological and social well-being
• End-of-life considerations

The investigators will ensure purposive sampling across key demographic and clinical variables which are available after a participant has expressed interest in the trial, with a minimum of 15 participants with ICD per subgroup (e.g., sex, age category, underlying cardiac condition). Data collection will continue until thematic saturation is reached within the overall cohort, followed by at least 5 additional interviews to confirm stability of themes. Subgroup representation is intended to capture relevant variation in lived experience and ensure applicability of findings across the ICD population. There is no subgroup analysis scheduled for partners as this cohort is considered secondary.

Predefined subgroups of interest:

• Sex
• Age: <35 years; 35 to 65 years; and > 65 years
• Underlying cardiac condition: congenital heart disease, hypertrophic cardiomyopathy, primary arrhythmia syndromes, Ischemic cardiomyopathy, Non-ischemic cardiomyopathy
• ICD shock history: appropriate ICD shock; inappropriate ICD shock; none
• Time since implantation: cut-off at 2 years
• ICD indication: primary vs secondary prevention
• Device type: single/dual/S-ICD vs cardiac resynchronization therapy

Inclusion Criteria:

• Adult (≥18 years) with an implanted ICD for either primary or secondary prevention of sudden cardiac death.
• At least 3 months have passed since ICD implantation.
• Sufficient cognitive ability and fluency in Dutch to provide informed consent and actively participate in the interview.
• Willing and able to participate in a one-time, individual in-depth interview of 30 to 60 minutes.

Exclusion Criteria:

• Current active severe psychiatric disorder or cognitive impairment that would interfere with meaningful participation as based on the medical history..
• Inability to provide informed consent due to legal, cognitive, or communicative limitations.
• Medical instability or terminal illness that, in the opinion of the treating physician or research team, precludes participation.
• Participation in another interventional trial that may influence psychological or behavioral outcomes relevant to this study.
• Participation in the QoL-ICD II trial with longitudinal QoL assessment.

Patients with any type of implantable cardioverter-defibrillator followed at UZ Leuven and their partners or primary caregivers.