Abstract 4140336: Reclassification of Congenital Heart Disease Severity via Cardiac Magnetic Resonance in a Tertiary Care Center in Latin-America

Introduction/Background: Cardiovascular magnetic resonance (CMR) has emerged as an invaluable non-invasive modality for accurate diagnosis and treatment in patients with congenital heart disease (CHD). Goals/Aims: Prevalence and reclassification of CHD severity by CMR referred to a tertiary-care center in Latin America (LATAM). Methods/Approach: Single-center retrospective study analyzing our institutional CMR database. The initial CMR requisition and final diagnoses were classified according to the 2018 American Heart Association (AHA) guidelines for CHD to establish a standardized diagnosis. We evaluated the change in severity between the pre-CMR and final CMR diagnoses and its relationship to mortality after reclassification. Descriptive statistics were used to present categorical variables as frequencies and percentages. A Sankey diagram illustrated changes in severity and mortality, and the association between reclassification and mortality using chi-square tests. Results/Data: Of 10,135 CMR performed between January 2016 and December 2023, 6.4% (656) were CHD, which increased over time (6.1% of all CMR referrals in 2016 up to 8.2% in 2023). 65.2% were adults with a mean age of 29.3 years (IQR 14-43), 55.8% female sex. Based on the pre-CMR diagnosis AHA classification, 30% were classified as simple, 43% as moderate, and 12.5% as complex. Reclassification of severity occurred in 33.2% of patients after the final CMR diagnosis, with the final CMR diagnoses reclassified into simple 16.5%, moderate 67.6%, and complex 15.9%. 14.5% of the cohort were initially undiagnosed with CHD and were diagnosed through CMR. Reclassification occurred most frequently in the simple group, with 56.1% reclassified to a more severe form and 7.7% becoming severe. The moderate group had the most significant increase in the severity of the final CMR diagnosis. Despite an observed increase in mortality among patients reclassified to moderate complexity, this did not reach statistical significance (p=0.68). Conclusion(s): Our study demonstrates that CMR is feasible in LATAM for diagnosing and reclassifying severity in CHD patients. Improved diagnostic yield of CMR may aid in properly diagnosing and directing CHD patients' care in our region.