Partial normalization of the heart rate (HR) response can take place some time after heart transplantation (HTx), but the extent to which this occurs, its time course, and functional significance remain unclear.
Seventy-seven heart transplantation patients underwent an exercise test at approximately 1, 6, and 12 mos after heart transplantation, consisting of a resting period, a submaximal exercise test, and a maximal exercise test with stair climbing, followed by a recovery period. An HR monitor was used for continuous surveillance of HR.
During the follow-up, HR at rest did not change, whereas all other HR parameters obtained during and after exercise improved, demonstrating a more rapid increase, a higher peak, and a more rapid decline in HR after stopping exercise. Age-predicted maximum HR at baseline was 73% ± 9%, improving to 83% ± 10% at 6 mos (P < 0.001) and to 90% ± 10% at 12 mos (P < 0.001), whereas the Chronotropic Response Index at baseline was 0.49 ± 0.15, improving to 0.67 ± 0.17 at 6 mos (P < 0.001) and to 0.81 ± 0.23 at 12 mos (P < 0.001).
Partial normalization of HR was achieved by 71% of heart transplantation patients at 12 mos, with significant changes occurring within 6 mos in most subjects. These findings should contribute to reducing the exercise restrictions that apply to the denervated heart.
From the Department of Cardiology, Oslo University Hospital HF Rikshospitalet, Oslo, Norway (KN, LG); VA Palo Alto Health Care System, Palo Alto, California (JM, KNC); Stanford University, California (JM); Department of Thoracic Surgery, Oslo University Hospital HF Rikshospitalet, Oslo, Norway (ORG); and Faculty of Medicine, Oslo University Hospital HF Rikshospitalet, Oslo, Norway (ORG, LG).
All correspondence and requests for reprints should be addressed to: Kari Nytrøen, PT, MSc, Department of Cardiology, Oslo University Hospital HF, Rikshospitalet, Postbox 4950 Nydalen, N-0424 Oslo, Norway.
Financial disclosure statements have been obtained, and no conflicts of interest have been reported by the authors or by any individuals in control of the content of this article. Funded, in part, by a grant from the South-East Health Region in Norway (Helse Sør-Øst). There are no financial benefits to the authors. Presented as an abstract at the 15th meeting of the International Congress of the World Confederation for Physical Therapy in Vancouver, June 2007, and another abstract was presented at the 31st annual meeting of The International Society of Heart and Lung Transplantation in San Diego and at EuroPRevent in Geneva, both in April 2011.