Digital cognitive behavioural therapy for cardiac anxiety following acute coronary syndrome: protocol for a randomised controlled trial comparing CBT to a digital lifestyle intervention

INTRODUCTION: Cardiac anxiety is common following acute coronary syndrome (ACS) and is characterised by fear of recurrence, heightened attention to cardiac sensations and avoidance of cardiac-related activities in daily life. It is associated with depression, reduced quality of life (QoL) and an adverse cardiac prognosis. We have developed a digital cognitive-behavioural therapy protocol for cardiac anxiety (CA-CBT) post ACS, previously evaluated in clinical trials including one randomised controlled trial (RCT), in which the intervention was compared to usual care. This protocol article describes a follow-up RCT, designed to further evaluate the efficacy of CA-CBT compared with an active control receiving a digital cardiac lifestyle intervention (CLI). METHOD AND ANALYSIS: Participants with ACS (ST-elevation myocardial infarction (STEMI)/non-STEMI/unstable angina ≥6 months prior) and elevated cardiac anxiety (Cardiac Anxiety Questionnaire; CAQ ≥18 and as per clinical interviews) (n=176) are randomised 1:1 to 8 weeks of CA-CBT or CLI. Primary outcome is change in cardiac anxiety, measured by the CAQ, from pre-intervention to post-intervention. Analyses will be conducted according to the 'intention-to-treat' principle, using hierarchical linear mixed-effects model, with random intercepts and including 10 weekly assessments collected during the treatment period. Secondary outcomes include disease-specific Quality of Life (Heart QoL), depression (Patient Health Questionnaire-9), insomnia (Insomnia Severity Index), in addition to both self-rated and accelerometer-measured physical activity. Secondary outcomes will be analysed using similar statistical methods. ETHICS AND DISSEMINATION: The study was approved by the Swedish Ethical Review Authority (Dnr 2023-07605-01), and the first patient enrolled on 7 March 2024. Recruitment is ongoing, and the completion date is expected to fall in the latter half of 2026. All participants receive information about the study and provide informed consent in accordance with ethical guidelines before inclusion. The results will be analysed at group level, and trial outcomes will be published in a peer-reviewed scientific journal, regardless of results. TRIAL REGISTRATION NUMBER: NCT06298864.