Uncorrected Proof Shiraz E-Med J. 2023 May; 24(5):e133319. Published online 2023 June 6. https://doi.org/10.5812/semj-133319. Research Article The Success of a New Protocol for Early Diagnosis and Management of Congenital Atrioventricular Block: A Follow-up Study of 15 Fetuses from November 2007 to August 2022 Mohsen Shahidi 1 and Abdorrahim Afkhamzadeh 2, * 1 Kurdistan University of Medical Sciences, Sanandaj, Iran 2 Health Research Center, Research Institute for Health Development, Kurdistan University of Medical Sciences, Sanandaj, Iran * Corresponding author: Health Research Center, Research Institute for Health Development, Kurdistan University of Medical Sciences, Sanandaj, Iran. Email: afkhama@gmail.com Received 2022 November 29; Revised 2023 April 30; Accepted 2023 May 14. Abstract Background: Congenital atrioventricular heart block (CAVB) is a relatively rare condition that can lead to long-term complications. Early diagnosis and management of CAVB is currently the ideal goal, particularly in high-risk pregnancies. Methods: The Fetal Heart Center at Kurdistan University serves as the primary referral center for pregnant mothers residing in the western region of Iran. Fifteen fetuses with CAVB were admitted between November 2007 and August 2022. They were referred for one or more of the following reasons: fetal bradycardia or arrhythmia, abnormal ultrasound findings, and previous maternal or fe- tal risk factors. After obtaining a complete medical history, we conducted fetal echocardiography and ordered testing for maternal Lo/Ra autoantibodies. Our therapeutic approach was based on the type of atrioventricular block (AVB), serum titer of Lo/Ra anti- bodies, and specific risk factors associated with each type of AVB. Consequently, we used a combination of different medications, including dexamethasone, Hydroxychloroquine (HCQ), IVIG, beta-agonists, and inotropes. Results: We admitted 15 fetuses with CAVB, including seven females (47%) and eight males (53%). Most of our cases had positive tests for Lo and Ra autoantibodies, with varying degrees of AVB. A previous fetal death was common in our case series, accounting for 47% of cases. Moderate and high antibody titers were present in 80% of our cases. Mild bradycardia was a relatively common finding in our cases of first and second-degree atrioventricular block (AVB), occurring in 33% of patients. All of the above-mentioned findings, commonly referred to as major risk factors, were used for either early evaluation or therapeutic goals. No cases with first-degree AVB developed a higher grade of AVB after our therapeutic approach. One fetus with second-degree AVB developed CCHB, and another with mixed second/third-degree AVB reverted to second-degree AVB with the use of appropriate medications. Conclusions: Our therapeutic approach for the current cases yielded satisfactory results. Subsequently, we attempted to develop a rudimentary approach for early managing and treating fetuses with various types of CAVB. We are looking forward to future multi- center studies. Keywords: Congenital Atrioventricular Heart Block, Complete Heart Block, Lo and Ra Autoantibodies, Fetal Bradycardia, Arrhythmia 1. Background Congenital atrioventricular heart block (CAVB) occurs during the fetal period due to various etiological factors (1). Congenital complete heart block (CCHB) is a condi- tion where the atrioventricular (AV) node is severely dam- aged, resulting in a slow heart rate of 40 to 80 beats per minute. This could be associated with cardiomegaly, heart failure, or even hydrops fetalis (2, 3). Although fetal death can be a devastating outcome, some fetuses successfully complete the prenatal period but may require permanent pacemaker (PPM) implantation after birth (4). The estimated frequency of CAVB is one in 10,000 to 20,000 newborns. However, fetal involvement may be more common due to overlooked cases resulting from fe- tal death (4, 5). Maternal autoantibodies, including La (Sjogren-syndrome-related antigen B, SSB) and Ro (Sjogren- syndrome-related antigen A, SSA) antigen antibodies, are the most commonly reported etiological factors of CAVB, with or without symptomatic maternal systemic lupus ery- thematosus (SLE) (6). Ro and La antigen antibodies are the primary rheumatoid autoantibodies that can cross the pla- centa and affect the fetal heart (7). Additionally, certain fe- tal congenital heart anomalies, such as congenitally cor- Copyright © 2023, Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.