BackgroundIn limited resource settings, identification of factors that predict the occurrence of pulmonary hypertension(PH) in children with atrial septal defect(ASD) is important to decide which patients should be prioritized for defect closure to prevent complication. Echocardiography and cardiac catheterization are not widely available in such settings. No scoring system has been proposed to predict PH among children with ASD. We aimed to develop a PH prediction score using electrocardiography parameters for children with ASD in Indonesia.MethodsA cross-sectional study reviewing medical record including ECG record was conducted among all children with newly diagnosed isolated ASD admitted to Dr Sardjito Hospital in Yogyakarta, Indonesia during 2016–2018. Diagnosis of ASD and PH was confirmed through echocardiography and/or cardiac catheterization. Spiegelhalter Knill-Jones approach was used to develop PH prediction score. Accuracy of prediction score was performed using a receiver operating characteristic (ROC) curve.ResultsOf 144 children, 50(34.7%) had PH. Predictors of pulmonary hypertension were QRS axis ≥120°, P wave ≥ 3 mm at lead II, R without S at V1, Q wave at V1, right bundle branch block (RBBB), R wave at V1, V2 or aVR > normal limit and S wave at V6 or lead I > normal limit. ROC curve from prediction scores yielded an area under the curve (AUC) 0.908(95% CI 0.85–0.96). Using the cut-off value 3.5, this PH prediction score had sensitivity of 76%(61.8–86.9), specificity 96.8%(91.0-99.3), positive predictive value 92.7%(80.5–97.5), negative predictive value 88.4%(82.2–92.6), and positive likelihood ratio 23.8(7.7–73.3).ConclusionsA presence of PH in children with ASD can be predicted by the simple electrocardiographic score including QRS axis ≥120°, P wave ≥3 mm at lead II, R without S at V1, Q wave at V1, RBBB, R wave at V1, V2 or aVR > normal limit and S wave at V6 or lead I > normal limit. A total score ≥ 3.5 shows a moderate sensitivity and high specificity to predict PH among children with ASD.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12887-023-04102-1.