Abstract 9556: Effect of High Intensity Interval Training in Heart Transplant Recipients - A Randomized Controlled Trial

Abstract

BACKGROUND High intensity interval training (HIIT) is an efficient form of exercise training in patients with coronary heart disease and heart failure, while heart transplant (HTx) recipients, mainly because of denervation, traditionally have not been exposed to HIIT. Even if many studies have documented effect of exercise in HTx recipients, VO_2peak remain below normal: 50 to 70% of predicted. Our hypothesis was that HIIT is an applicable and safe form of exercise in heart transplant (HTx) recipients, and that it would markedly improve VO_2peak. Secondarily, we wanted to evaluate central and peripheral mechanisms behind a potential VO_2peak increase.

METHODS Forty-eight clinically stable HTx recipients >18 years old and 1-8 years after HTx underwent maximal exercise testing on a treadmill, muscle strength testing, echocardiography and quality of life questionnaires. They were randomized to either exercise group (a one-year HIIT-program) or control group (usual care).

RESULTS The mean±SD age was 51±16 years, 71% were male and time since HTx was 4.1±2.2 years. The mean VO_2peak difference between groups at follow-up was 3.6 [2.0, 5.2] mL/kg/min (p<0.001). The exercise group had achieved 89.0±17.5% of predicted VO_2peak vs. 82.5±20.0% in the control group (p<0.001). In addition, the exercise group improved their muscular exercise capacity significantly (p<0.001) and had subjectively significant better general health (p<0.001). There were no changes in cardiac function measured by echocardiography.

CONCLUSIONS The present study documents that a long-term, partly supervised and community-based HIIT-program is an applicable, effective and safe way to improve VO_2peak, muscular exercise capacity and quality of life in HTx recipients. The results indicate that HIIT should be more frequently used among stable HTx recipients in the future.