1KU Leuven Cardiovascular Sciences Leuven, Belgien; 2KU Leuven Rehabilitation sciences Leuven, Belgien; 3KU Leuven Pediatric Oncology Leuven, Belgien; 4KU Leuven Pediatric Cardiology Leuven, Belgien; 5University Hospital Gasthuisberg Dept. of Cardiology Leuven, Belgien
Background: Many childhood cancer survivors do experience limitations of their cardiorespiratory fitness (CRF) that might be related to an underlying undetected cardiac dysfunction. Current conventional echocardiographic parameters are not sensitive enough to detect early signs of treatment related cardiac dysfunction. High frame rate echocardiography enables the measurement of natural myocardial shear waves (SW) that occur after mitral valve closure (MVC) and reflect changes in myocardial stiffness, a key factor in diastolic function.
Purpose: This study aimed at testing the ability of Shear Wave Elastography (SWE) to detect alterations in myocardial stiffness among childhood cancer survivors compared to healthy peers.
Methods: Thirty-two childhood cancer survivors (mean 20 ±3 years; range 15-27 years old) who received chemotherapy (mean time after treatment: 4 ±2 years) and thirty-two age & sex-matched healthy volunteers (HV) were recruited. All participants underwent an incremental, symptom limited cardiopulmonary exercise test on a treadmill measuring peak oxygen consumption (VO2 peak). After exercise, both conventional as well as high frame rate echocardiographic images (typical 1200 frames/second) were acquired using a modified commercial echocardiography machine. An anatomical M mode was drawn along the ventricular septum, and tissue Doppler acceleration maps were extracted to measure SW velocities after MVC (Figure 1).
Results: Among Cancer survivors, left ventricular ejection fraction (LVEF) was normal (56 % ±4). Similarly, diastolic function and filling pressures were within normal range (mitral E/e’= 5.7 ±1). Global longitudinal strain (GLS) was significantly reduced compared to HV (17.6 % ±1.9 vs 20.7 % ±0.9, p <0.001). SW velocities were significantly higher in cancer survivors than in HV (3.6 ±0.5 m/s vs 2.9 ±0.2 m/s respectively; p <0.001) (Figure 2). Interestingly, SW velocities among cancer survivors showed moderate significant negative correlation with the VO2 peak (r= -0.405, p =0.021), indicating increasing myocardial stiffness as the cardiorespiratory fitness declined. (Figure 3).
Conclusions: Natural myocardial SW velocities were significantly higher in cancer survivors and significantly related to cardiorespiratory fitness. Our data indicate, that increased myocardial stiffness may explain part of the decrease in CRF in this population. Echocardiographic shear wave elastography appears as a promising non-invasive tool for early detection of diastolic dysfunction in follow-up of childhood cancer survivors.
Figure 1.
Figure 2.
Figure 3.