High Intensity Interval Training Reduces Progression of Cardiac Allograft Vasculopathy among Heart Transplant Recipients – Results from a Randomized Controlled Trial

Abstract

Purpose Cardiac allograft vasculopathy (CAV) is a progressive form of atherosclerosis occurring in heart transplant (HTx) recipients, contributing to increased morbidity and mortality. High intensity interval training (HIIT) is effective in patients with coronary artery disease, resulting in reduced progression of atherosclerosis, but its effect in HTx has not been investigated. We hypothesized that HIIT also would reduce the progression of CAV in HTx patients. Methods and Materials Forty-three clinically stable HTx recipients >18 years old, were randomized to either HIIT or control group (standard care) for one year. Baseline and one year maximal exercise testing on a treadmill, together with measurement of inflammatory biomarkers and intravascular ultrasound (IVUS), were performed. Results The mean±SD age was 51±16 years, 67% were male and time post HTx was 4.0±2.2 years. VO 2peak (mL/kg/min) improvement was 2.9±2.9 in the HIIT group as compared to -0.3±2.9 in the control group ( p 0.001), corresponding to 89% and 82% of expected VO 2peak level, respectively. IVUS analysis revealed a mean increase [95%CI] in percent atheroma volume (PAV) of 0.9 [−0.3, 1.9]% in the HIIT group, as compared to 2.5 [1.6, 3.5]% in the control group ( p =0.021). Similarly, mean increase [95%CI] in maximal intimal thickness (MIT) was 0.02 [-0.01, 0.04] mm in the HIIT group as compared to 0.05 [0.03, 0.08] mm in the control group ( p =0.054). Qualitative plaque progression (virtual histology parameters) and inflammatory activity (biomarkers) were similar between the two groups during the study period. Conclusions High intensity interval training among maintenance HTx recipients resulted in a significantly slower rate of CAV progression as assessed by PAV, and borderline significant by MIT. Furthermore, improvement in VO 2peak was significantly greater in patients treated with HIIT, suggesting that routine implementation of exercise protocols could help reduce morbidity and mortality among HTx recipients.