Effect of High-Intensity Interval Training in De Novo Heart Transplant Recipients in Scandinavia: One-Year Follow-Up of the HITTS Randomized, Controlled Study

Background: There is no consensus on how, when, or at what intensity exercise should be performed after heart transplantation (HTx). We have recently shown that high-intensity interval training (HIT) is safe, well tolerated, and efficacious in the maintenance state after HTx, but studies have not investigated HIT effects in the de novo HTx state. We hypothesized that HIT could be introduced early after a HTx, and that it could lead to clinically meaningful increases in exercise capacity and health-related quality of life (HRQoL). Methods: This multicenter, prospective, randomized, controlled trial included 81 patients, mean 11 weeks (range 7- 16) after a HTx. Patients were randomized, 1:1, to either nine months of HIT (4x4-min intervals at 85-95% of peak effort) or moderate intensity continuous training (MICT) (60-80% of peak effort). The primary outcome was the effect of HIT vs. MICT on the change in aerobic exercise capacity, assessed as the VO2peak. Secondary outcomes included tolerability, safety, adv...