Abstract Aim: To evaluate systolic and diastolic cardiac function in children who had cardiomyopathy induced by ectopic atrial tachycardia (EAT). Methods: Twenty-two pediatric patients who had cardiomyopathy induced by EAT and 25 age-matched controls were recruited in this case-control study. The patients were examined after rhythm control and normalization of their left ventricular systolic function. Different echocardiographic modalities including tissueDoppler imaging and twodimension speckle tracking echocardiography were utilized to assess the ventricular and atrial function. Results: The patients’ median age was 51 months (interquartile range: 28.5–84 months). The median time interval required for normalization of left ventricular ejection fraction (EF) among patients was 1.5 months (interquartile range: 1.5–2.12 months). Compared to controls, patients had a significantly highermedian left ventricularmyocardial performance index (MPI) at the interventricular septum (0.44 vs. 0.38, p = .001) and left ventricular lateral wall (0.46 vs. 0.32, p = .0001). The median right ventricular MPI of the patients’ group was significantly higher when compared to the control group (0.34 vs. 0.26, p = .0001). The median right atrial (RA) reservoir function in patients was significantly reduced compared to controls (30% vs. 36.63%, p = .007). Conclusions: Shortly after rhythm normalization and restoration of left ventricular EF, using tissue Doppler imaging and two-dimension speckle tracking echocardiography, children who had cardiomyopathy induced by EAT continue to have left ventricular diastolic dysfunction, right ventricular dysfunction, and reduced RAreservoir function.