Cardiovascular Symptom Tracking Among Patients With Cancer in Cardio-Oncology Care: Qualitative Study Using the Capability, Opportunity, Motivation–Behavior (COM-B) Framework

Background: Cardiovascular disease is a leading noncancer cause of morbidity and mortality among individuals diagnosed with cancer. Although modern cancer therapies have improved survival, many are associated with cardiotoxic effects that increase the risk of cardiovascular complications. Early identification of cardiovascular symptoms and signs may support timely clinical management. However, tracking cardiovascular health during cancer care can be complex for both patients and medical team participants, and important indicators, such as blood pressure changes, heart rate variability, fluid retention, chest pain, or new-onset fatigue, may be missed between clinic visits. Mobile health technologies offer potential tools to facilitate remote monitoring, yet behavioral factors influencing cardiovascular tracking in cardio-oncology remain insufficiently understood. Objective: This study aimed to identify barriers and facilitators influencing cardiovascular symptom tracking among patients with cancer and medical team participants using the capability, opportunity, motivation-behavior (COM-B) framework. Methods: This qualitative descriptive study included adult patients with cancer (n=12) receiving cardiotoxic therapies and members of their health care teams (n=12), including oncologists, nurses, advanced practice providers, and allied health professionals. Participants were recruited from a cardio-oncology clinic. Semistructured interviews explored perceptions of tracking cardiovascular symptoms and signs. Data were analyzed using rapid qualitative analysis and organized according to COM-B domains. The study received ethical approval, and participants provided informed consent. Results: Patients with cancer and medical team participants described cardiovascular symptom tracking as a shared responsibility. Capability-related themes included uncertainty regarding which symptoms to monitor, appropriate thresholds for concern, and variability in communication practices. Opportunity-related themes included time pressures, competing clinical demands, and the influence of patient-medical team participant relationships and social support. Motivation-related themes reflected perceived benefits of tracking, including reassurance for patients and improved clinical insight for medical team participants, alongside concerns about information burden and unclear actionability. Both groups expressed interest in digital tools that provide clear guidance, defined response pathways, and integration within health care workflows. Conclusions: Cardiovascular symptom tracking in cancer care is shaped by interrelated behavioral and contextual factors affecting both patients and medical team participants. Digital systems intended to support tracking should address knowledge clarity, workflow integration, and actionability of reported information. Understanding these determinants may inform the design and implementation of cardiovascular monitoring strategies in cardio-oncology settings.