@Article{CHD.2020.011287,
AUTHOR = {Shivani M. Bhatt, Michael L. O’Byrne, Michael McBride, Stephen M. Paridon, Elizabeth Goldmuntz, Laura Mercer-Rosa},
TITLE = {Chronotropic Response and Pulmonary Function are Associated with  Exercise Performance in Children and Adolescents with Repaired Tetralogy  of Fallot Independent of Cardiac Function},
JOURNAL = {Structural and Congenital Heart Disease},
VOLUME = {15},
YEAR = {2020},
NUMBER = {2},
PAGES = {101--115},
URL = {http://www.techscience.com/schd/v15n2/39430},
ISSN = {3071-1738},
ABSTRACT = {<b>Objective:</b> The determinants of exercise capacity in repaired tetralogy of 
Fallot (rTOF) are multifactorial and remain incompletely understood. This study 
sought to evaluate the association of chronotropic response with exercise parameters
and investigate the determinants of heart rate reserve (HRR) in a cohort of children 
and adolescents with rTOF. <b>Design:</b> We retrospectively analyzed patients with 
rTOF, age 8–18 years, who underwent cardiac magnetic resonance (CMR) and 
cardiopulmonary exercise test (CPET) for research purposes. Linear regression 
models were performed to test associations among clinical, CMR and CPET 
parameters. Outcomes included percent-predicted maximum VO<sub>2</sub> (%mVO<sub>2</sub>) and 
HRR. <b>Results:</b> A total of 148 patients were included (mean age 12.3 ± 3.1 years). 
The majority of patients had TOF with pulmonary stenosis (80%) and underwent 
transannular patch TOF repair (78%). Median age at surgical repair was 4.2 months
(IQR 1.2, 8.4). There was preserved RV ejection fraction (60.4 ± 8.3%) and 
moderate pulmonary insufficiency (regurgitant fraction 35.2 ± 16.6 %). On 
CPET, %mVO<sub>2</sub> was overall diminished (76.5 ± 17.9 %), and % predicted forced 
vital capacity (FVC) was diminished on spirometry. HRR, FVC and ability to reach 
maximum effort were independently associated with greater %mVO<sub>2</sub>. FVC, net 
forward flow in the main pulmonary artery/m<sup>2</sup>
, and reaching maximum effort were 
associated with greater HRR, independently of RV volume, degree of PI and RV 
ejection fraction. <b>Conclusions:</b> In patients with rTOF, HRR and pulmonary function
(FVC) are more important contributors to exercise performance than right 
ventricular function. Interventions to improve chronotropic health and pulmonary 
function should be explored.},
DOI = {10.32604/CHD.2020.011287}
}