Abstract 9402: Diffuse Myocardial Fibrosis Negatively Correlates with Exercise Capacity in Children with Subclinical Anthracycline Cardiotoxicity
Background The effectiveness of anthracycline chemotherapy in improving survival is limited by late cardiotoxicity. The aim of this study was to examine novel cardiac MRI and echocardiography measures to detect subclinical cardiotoxicity in childhood cancer survivors, and to determine its relationship to exercise capacity.
Methods Thirty patients (15±3years, 50% male), 8±5 years after anthracycline therapy (cumulative dose 197±84 mg/m2), underwent cardiac MRI, echocardiography and cardiopulmonary (cycle ergometer) exercise testing (VO2peak). Cardiac MRI assessed volumetric function, mass, and myocardial extra-cellular volume (ECV), a measure of diffuse fibrosis based on changes in blood and myocardial T1 values pre and post gadolinium. Tissue Doppler annular velocities (E’, A’) and peak circumferential and longitudinal strain, strain rate (SR) and torsion, from speckle tracking, were compared to 35 healthy controls (13±4 years). Data (mean ± SD) was analysed using Pearson's product-moment coefficient and unpaired t-tests (p<0.05).
Results Patients were asymptomatic with normal LVEF (59±7%) but VO2peak was 15% lower than age and gender determined healthy predicted values. Myocardial ECV was inversely correlated with mass/volume ratio (r = -0.5, p<0.01), and VO2peak (r = -0.5, p<0.01), and lower VO2peak correlated with increased cumulative dose (r = 0.4, p<0.05). Echocardiographic measures of systolic function were significantly reduced compared to controls (decreased circumferential and longitudinal strain, longitudinal SR and torsion, p<0.01). Diastolic dysfunction was evident with decreased circumferential and longitudinal diastolic SR and decreased annular velocities (p<0.01) relative to controls. There was no correlation between echocardiographic parameters and ECV or VO2peak.
Conclusion Diffuse myocardial fibrosis (increased ECV) is correlated with reduced mass/volume ratios and VO2peak in children post anthracyline. While there were abnormalities of systolic and diastolic function, these metrics did not correlate with ECV or VO2peak. Myocardial ECV provides a non-invasive early marker of ventricular remodelling that is related to exercise capacity which may be of prognostic value in childhood cancer survivors.
- © 2011 by American Heart Association, Inc.