Copyright ©The Author(s) 2018. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Transplant. Feb 24, 2018; 8(1): 1-12
Published online Feb 24, 2018. doi: 10.5500/wjt.v8.i1.1
Importance of physical capacity and the effects of exercise in heart transplant recipients
Marianne Yardley, Lars Gullestad, Kari Nytrøen
Marianne Yardley, Lars Gullestad, Kari Nytrøen, Department of Cardiology, Oslo University Hospital Rikshospitalet, Oslo 0424, Norway
Marianne Yardley, Lars Gullestad, Kari Nytrøen, Faculty of Medicine, University of Oslo, Oslo 0316, Norway
Author contributions: Gullestad L and Nytrøen K designed the research; Yardley M and Nytrøen K has performed different parts of the research, analyzed the data and drafted the paper; all authors equally contributed to the final analyses, further drafting and critical revision and editing, and final approval of the final version.
Conflict-of-interest statement: No potential conflicts of interest. No financial support.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Correspondence to: Dr. Kari Nytrøen, PhD, Senior Postdoctoral Fellow, Department of Cardiology, Oslo University Hospital Rikshospitalet, Postbox 4950 Nydalen, Oslo 0424, Norway.
Telephone: +47-951-89935 Fax: +47-230-73917
Received: November 17, 2017
Peer-review started: November 17, 2017
First decision: November 30, 2017
Revised: December 12, 2017
Accepted: December 28, 2017
Article in press: December 28, 2017
Published online: February 24, 2018

One of the most important prognostic factors in heart failure patients is physical capacity. Patients with very poor physical performance and otherwise eligible, may be listed as candidates for heart transplantation (HTx). After such surgery, life-long immunosuppression therapy is needed to prevent rejection of the new heart. The dark side of immunosuppression is the increased risk of infections, kidney failure, cancer and advanced atherosclerosis (cardiac allograft vasculopathy), with the two latter conditions as the main causes of later mortality. In a worldwide perspective, 50% of the HTx patients survive past 10 years. Poor aerobic capacity prior to graft deterioration is not only limited to the failing heart, but also caused by peripheral factors, such as limited function in the skeletal muscles and in the blood vessels walls. Exercise rehabilitation after HTx is of major importance in order to improve physical capacity and prognosis. Effects of high-intensity interval training (HIT) in HTx recipients is a growing field of research attracting worldwide focus and interest. Accumulating evidence has shown that HIT is safe and efficient in maintenance HTx recipients; with superior effects on physical capacity compared to conventional moderate exercise. This article generates further evidence to the field by summarizing results from a decade of research performed at our center supported by a broad, but not strict formal, literature review. In short, this article demonstrates a strong association between physical capacity measured after HTx and long-term survival. It describes the possible “HIT-effect” with increased levels of inflammatory mediators of angiogenesis. It also describes long-term effects of HIT; showing a positive effect in development of anxiety symptoms despite that the improved physical capacity was not sustained, due to downregulation of exercise and intensity. Finally, our results are linked to the ongoing HITTS study, which investigates safety and efficiency of HIT in de novo HTx recipients. Together with previous results, this study may have the potential to change existing guidelines and contribute to a better prognosis for the HTx population as a whole.

Keywords: High-intensity interval training, Peak oxygen uptake, Heart transplantation, Survival, Prognosis, Angiogenesis, Inflammation, Physical capacity, Exercise

Core tip: Despite the positive effects of regular exercise after heart transplantation (HTx), HTx recipients’ physical capacity remains subnormal, and a strong association between physical capacity and survival has been demonstrated. Thus, the positive effects of high-intensity interval training (HIT) are a growing field of research, attracting worldwide focus and interest. Although the “HIT-effect” is not fully understood, a possible contributing factor is the increased levels of inflammatory mediators of angiogenesis generated during exercise. More high-quality research is strongly warranted, but ongoing studies already have the potential to change existing guidelines and contribute to a better prognosis for the HTx population.