Digital Cognitive Behavioral Therapy for Cardiac Anxiety Following Acute Coronary Syndrome: Protocol for a Randomised Controlled Trial Comparing CBT to a Digital Lifestyle Intervention

Abstract 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 randomized 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 to an active control receiving a digital cardiac life-style intervention (CLI). Method and analysis Participants with ACS (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-to post-intervention. Analyses will be conducted according to the ‘intention-to-treat’ principle, using hierarchical linear mixed-effects model, with random intercepts, and include ten weekly assessments collected during the treatment period. Secondary outcomes include disease-specific Quality of Life (Heart-Qol), depression (PHQ-9) insomnia (ISI), 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 March 7 2024. Recruitment is ongoing and is expected to conclude 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 Registered at ClinicalTrials.gov, ID: NCT06298864 Strengths and limitations To our knowledge, this is the first exposure-based CBT intervention specifically targeting cardiac anxiety following ACS, addressing a modifiable psychological risk factor with relevance for secondary prevention. The use of an active control group helps account for non-specific effects. However, overlapping components, such as behavioural strategies to increase physical activity, between the CBT and lifestyle interventions poses a risk of diluting between-group differences. The use of objective physical activity measures, assessed via accelerometry, alongside well-validated self-report instruments, strengthens the validity of the outcome measurements. The study procedures include a multidisciplinary assessment and collaborative treatment delivery to ensure patient safety. Manual-based treatment delivery with therapist support ensures minimal therapist drift while maintaining an individualised approach. Using the same therapist across both study arms helps reduce the risk of therapist-related confounding effects.