Background: Unlike adult patients, the utility of cardiopulmonary exercise testing (CPET) in children as a prognostic tool is unclear. We sought to examine the associations of CPET with outcomes in children with dilated cardiomyopathy (DCM).
Methods: This was a single-center, retrospective review of children with DCM who underwent CPET. The primary endpoint for this study was a time-dependent composite outcome of hospitalization for management of decompensated heart failure, initiation of mechanical circulatory support, heart transplant, or death.
Results: We examined 52 children with DCM who underwent CPET at median age 12.6 years (interquartile range [IQR], 9.9-14.6 years). At first CPET, the median peak heart rate was 80% (IQR, 70-88%) of predicted, median peak oxygen consumption 62% (IQR, 45-77%) of predicted, and median minute ventilation/carbon dioxide production slope 34.9 (IQR, 27.9-39.4). Eighteen (35%) patients reached the composite outcome during follow-up. Univariable factors associated with the composite outcome included: lower peak heart rate predicted, lower blood pressure response, lower peak oxygen consumption predicted, and higher minute ventilation/carbon dioxide production slope. The association between exercise performance and composite outcome was linear; thus, no reliable cutoff point could be identified. Serial CPET had been performed in 30 patients; clinically, those with deterioration of exercise capacity had poorer outcomes.
Conclusions: Cardiopulmonary exercise testing is feasible in children with DCM and is useful to predict outcomes. The finding of lower exercise capacity and lower blood pressure response should prompt closer follow-up. In those with serial testing, a decline in exercise capacity may be a marker of clinical deterioration.
In a single-center retrospective study of 52 children with both dilated cardiomyopathy and cardiopulmonary exercise training (CPET), the authors demonstrate an association between lower exercise capacity and poor outcome, which could serve as a marker of clinical deterioration.
1 Cardiology Service, Department of Paediatric Subspecialties, KK Women’s and Children’s Hospital, Singapore.
2 Department of Pediatrics, University of Toronto, The Labatt Family Heart Centre, The Hospital for Sick Children, Toronto, Ontario, Canada.
3 Division of Pediatric Cardiology, Stollery Children’s Hospital, Edmonton, Alberta, Canada.
Received 30 April 2016. Revision received 21 December 2016.
Accepted 19 January 2017.
The authors declare no funding or conflicts of interest.
C.K.C. participated in research design, data collection, data analysis, and writing of the article. C.M. participated in statistical analysis and writing of the article. J.L.R. participated in performance of the research and approved the final article. P.F.K. participated in performance of the research and approved the final article. B.W.M. participated in performance of the research, reviewed the statistical analyses, and approved the final article. J.C. acted as the senior author, conceptualized and designed the study, reviewed the analyzed data, reviewed and revised the article, and approved the final article.
Correspondence: Ching Kit Chen, MBBS, MRCPCH, Cardiology Service, Department of Paediatric Subspecialties KK Women's and Children's Hospital 100 Bukit Timah Road, 229899, Singapore. (firstname.lastname@example.org).