Consumer technology is increasingly used to support the self-care of atrial fibrillation (AF), a chronic heart condition that affects physical, emotional, and mental health due to its unpredictability, symptoms, and complications. Through interviews with 29 adults self-tracking while living with AF, we found that consumer technology enabled participants to outsource bodily awareness to their ’digitised heart,’ facilitating innovative pill-in-pocket interventions and empowering negotiation in shared decision-making. Drawing on phenomenology, we introduce ’Bodily Doubt’ to explain how uncertainty about the body shapes the use of technology in chronic illness and how the use of technology influences uncertainty. Technology mediates ’Bodily Doubt’ both by providing reassurance and exacerbating it, particularly when technology fails to adapt to disease progression. Our findings have implications for understanding how technology influences the lived experience of illness, challenging experiential concepts of lived experience in self-tracking and design that foregrounds the experience of the lived body.

Despite their nonclinical origins, wearables are emerging as valuable tools in supporting the diagnosis of cardiovascular disease, one of the leading causes of death worldwide. Diagnostic data once only available via a cardiologist is now available to consumers simply by wearing a smartwatch, so understanding how smartwatches currently support diagnosis is important for healthcare providers and for the designers of increasingly sophisticated personal informatics technology. We conducted a qualitative study comprising interviews and analysis of posts on an online community of accounts of smartwatch assisted cardiac diagnosis. Our findings reveal how smartwatches bridge a current gap in clinical diagnostic modalities, facilitating a diagnostic journey instigated and shaped by the interplay of self-collected data, bodily self-awareness, and increasing clinical acceptance. These insights focus attention on the consequences of the democratisation of health data, with ethical and design implications for health providers, consumer electronic companies, and third-party application designers.