Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 52 5 2023 05 08 1031 1037 Shahla Ansari Damavandi Department of Hematology-Oncology, Ali Asghar Children's Hospital, Iran University of Medical Sciences, Tehran, Iran Mozhgan Parsaee Echocardiography Research Center of Rajaee Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran Milad Ahmadi Marzaleh Department of Health in Disasters and Emergencies, School of Health Management and Information Sciences, Shiraz University of Medical Sciences, Shiraz, Iran Maryam Shamspour Pediatric Hematology and Oncology, Iran University of Medical Sciences, Tehran, Iran 2021 10 25 2021 12 25 Background: Thalassemia is the most common inherited anemia in worldwide. Heart failure is the most common cause of mortality and morbidity in patients with major and intermedia β-thalassemia. This study aimed to evaluate the effect of oral administration of L-arginine on the improvement of systolic Pulmonary Artery Pressure (PAP) and cardiac function in patients with major and intermedia β-thalassemia. Methods: This randomized clinical trial was done on 88 patients with β-thalassemia admitted to Ali Asghar Hospital, Tehran, Iran between 2020 and 2021. Echocardiography was performed for all the patients before the intervention. Afterwards, the patients were randomly divided into two groups of placebo and L-arginine. The patients underwent echocardiography after eight weeks and were compared with respect to the results. Results: The mean blood transfusion interval was 20.21 d in the placebo group and 17.14 d in the L-arginine group (P=0.082). The results revealed no significant difference between the two groups regarding the mean levels of Hemoglobin (Hb) and ferritin, frequency of splenectomy. However, the mean PAP significantly decreased from 32.88 to 26.02 in the L-arginine group (P=0.009), but did not change in the placebo group. Nonetheless, no significant change was observed in the mean Ejection Fraction (EF) before and after L-arginine administration. Conclusion: L-arginine administration prevented the increase of PAP and was effective in preventing cardiovascular disorders including increased systolic PAP in patients with major and intermedia B-thalassemia. However, the results have to be confirmed in further studies with larger sample sizes.   https://ijph.tums.ac.ir/index.php/ijph/article/view/26668 https://ijph.tums.ac.ir/index.php/ijph/article/download/26668/7937