Background <p>Detecting anthracyclines’ cardiotoxicity through Speckle-Tracking Echocardiography and Tissue Doppler Imaging, instead of standard echocardiographic methods, has become widespread. Speckle tracking echocardiography represents a non-Doppler-based method for an objective quantification of myocardial deformation. Our aim is to evaluate these methods in childhood solid tumours taking into account the use of dexrazoxane.</p> Methods <p>A total of 52 patients underwent at least two echocardiographic evaluations. The first was conducted pre-treatment and the second post-anthracycline at the dose of 100–300 mg/m² (low to moderate dose). Some of the patients (<i>n</i> = 22) underwent a third echocardiographic evaluation at a dose of &gt; 300 mg/m² (high dose). Additionally, some patients (<i>n</i> = 38) were unable to obtain dexrazoxane. So, further analyses were retrospectively conducted based on dexrazoxane use.</p> Results <p>Among the total patients who did not receive dexrazoxane, myocardial septal systolic and diastolic Doppler velocities were significantly lower. In addition, myocardial deformation parameters substantially worse in the post-treatment evaluation, unlike those who used dexrazoxane. However, impairment in myocardial deformation parameters was not significant at the high dose measurement. For the patients who received dexrazoxane, myocardial systolic and diastolic Doppler velocities significantly lower in the high dose measurement than in the baseline. This study showed no significant differences in myocardial performance index values between baseline and early post-treatment measurements.</p> Conclusion <p>Until a high dose, using dexrazoxane may prevent left ventricular systolic dysfunction and possible subtle pulmonary hypertension. Using myocardial performance index values in the early treatment period may not be reliable.</p>