Abstract Background Chagas disease (CD), a parasitic disease caused by Trypanosoma cruzi. Parasite persistence is crucial in the development and progression of Chagas cardiomyopathy that occurs in 30% of untreated patients. Methods and findings A cohort of 95 CD treated children, with at least 6 years post-treatment follow up, was evaluated. Median after treatmeant follow-up was 10 years. At the time of the last visit a group of non infected subjects were also included as a control for cardiological studies. During follow-up, the majority of treated subjects 59/61 (96%) achieved negative parasitemia by qPCR at the end of treatment. A decrease in T. cruzi antibodies titers were observed and seroconversion by two conventional serology tests (IHA, ELISA) occurred in 53/95 (56%). Holter showed alterations in 3/95 (3%) of treated patients: isolated ventricular extrasystoles and nocturnal sinus bradycardia (one patient); asymptomatic and vagal related 1st and 2nd degree AV block (one patient); and complete right bundle branch block (cRBBB) (one patient). Only the last one is probably related to CD involvement. 2D speckle tracking echocardiography was conducted in 79/95 (83%) patients and no alterations in myocardial contractility were observed. In the non infected group Holter evaluations showed similar non pathological results in 3/28 (10%) of subjects: isolated ventricular premature beats (2 patients); asymptomatic 2nd degree AV block with Wenckebach sequences during night time (one patient). 2D speckle tracking echocardiography was conducted in 25/28 (89%) with no alterations. Conclusions After long term follow-up of a cohort of treated children for CD, a good parasiticidal treatment effect and a low incidence of cardiological lesions, related to Chagas disease, were observed. These results suggest a protective effect of treatment on the development of cardiological lesions and strengthen the recommendation of early diagnosis and treatment of infected children. Trial registration ClinicalTrials.gov NCT04090489.