Evaluation of high intensity interval training in patients with a right ventricle to pulmonary artery conduit in a randomized controlled trial – Rationale and design of the ‘Right HIIT’ study

BACKGROUND: Exercise training is a promising, relatively low cost strategy to optimize exercise capacity, primarily studied in patients with tetralogy of Fallot and Fontan physiology. However, rare and complex biventricular disorders are understudied. High intensity interval training (HIIT) is a time-efficient alternative to the more commonly studied aerobic training. Despite group level improvements in exercise capacity, individual variation suggests the existence of responders and non-responders to exercise training. We therefore designed a HIIT intervention trial for patients with complex outflow tract disorders aimed to test efficacy and identify predictors of response. METHODS: The Right HIIT study is a multicenter, randomized controlled trial aiming to enroll 38 patients aged 12 to 45 years with a right ventricle to pulmonary artery conduit. Participants will be randomized to a 12-week home-based HIIT program (intervention) or standard of care (SoC) group. The primary endpoint is change in peak oxygen consumption from baseline to 12 weeks. Secondary endpoints include other cardiopulmonary exercise testing and imaging parameters, blood biomarkers, gut microbiome composition, quality of life and physical activity levels. After the randomized phase, the SoC group will receive the HIIT program, with repeated data collection after 12 weeks. Thus, pre-post HIIT data will be available in all patients, for the purpose of supportive analyses and identifying predictors of response. CONCLUSION: The Right HIIT study will analyze whether a HIIT program improves exercise capacity in patients with a right ventricle to pulmonary artery conduit and which factors are associated with the ability to improve exercise capacity.