High-Intensity Interval Training vs Moderate Continuous Training in Adults With Congenital Heart Disease: A Randomized Controlled Trial.

BACKGROUND

Exercise capacity is reduced in adults with congenital heart disease (ACHD) and associated with adverse prognosis. Our objective was to explore the efficacy of high-intensity interval training (HIIT) compared with moderate continuous training (MCT) on improving exercise capacity in this population.

METHODS

A 3-arm single centre randomized controlled trial was conducted to evaluate the effect of 12 weeks of exercise training (HIIT vs MCT) vs control in ACHD. The primary outcome was a change in peak oxygen uptake (VO2) between baseline and 12 weeks. Secondary outcomes included exercise-related adverse events, changes in cardiac structure and function, and quality of life scores.

RESULTS

Thirty-two ACHD were included, with a mean age of 32 ± 11 (range, 24-39) years, 56% were male with average peak VO2 of 27.8 ± 7.0 mL/kg/min at baseline. Exercise training for 12 weeks with HIIT significantly increased peak VO2 by 3.7 ± 3.8 mL/kg/min (P = 0.001), whereas MCT improved peak VO2 by 2.1 ± 3.1 mL/kg/min (P = 0.01), compared with no change in the control group, -1.3 ± 3.0 mL/kg/min (P = 0.44). No adverse events occurred with exercise training. Cardiac magnetic resonance imaging-derived ventricular volumes and ejection fraction were unchanged after exercise training. However, HIIT increased left ventricular mass by 8% (P = 0.02). Exercise training had no effect on quality of life.

CONCLUSIONS

HIIT and MCT improved peak VO2 and were feasible, safe and did not produce adverse cardiac remodelling in ACHD. HIIT was associated with an adaptive increase in left ventricular mass and should be considered as part of comprehensive cardiac rehabilitation.

CLINICAL TRIAL REGISTRATION: NCT07546227.