High-intensity interval training before elective abdominal aortic aneurysm repair: A randomised controlled feasibility trial

Background: This study assessed the feasibility of a pre-operative high-intensity interval training (HIT) programme in patients undergoing elective AAA repair. Methods: In this feasibility trial, participants were allocated by minimisation to pre-operative HIT (n=27) or usual care (n=26). The HIT group were offered three exercise sessions per week for 4 weeks, and weekly maintenance sessions if surgery was delayed. Feasibility and acceptability outcomes were rates of screening, eligibility, recruitment, retention, outcome completion, adverse events, and exercise adherence. Data on exercise enjoyment (PACES), cardiorespiratory fitness (anaerobic threshold and peak oxygen uptake), quality of life, post-operative morbidity and mortality, duration of hospital stay, and healthcare utilisation were also collected. Results: Screening, eligibility, recruitment, retention, and outcome completion rates were 100% (556/556), 43% (240/556), 22% (53/240), 91% (48/53), and 79-92%, respectively. Overall exercise session attendance was 76% (276/364), and the mean post-programme PACES score was 98/119 (‘enjoyable’; SD 19); however, the intensity of exercise was generally lower than that intended. Mean anaerobic threshold after exercise training (adjusted for baseline score and minimisation variables) was 11.9 mL/kg/min in exercise versus 11.6 mL/kg/min in control (difference = 0.3 mL/kg/min; 95% CI, -0.4 to 1.1). There were trivial-to-small differences in post-operative clinical and patient-reported outcomes between the exercise and control groups. Conclusions: Despite the intensity of exercise being generally lower than intended, the findings support the feasibility and acceptability of both pre-operative HIT and the trial procedures. An appropriately-powered, multi-centre trial is required to establish the clinical and cost-effectiveness of the intervention.