Cardiovascular magnetic resonance reference ranges for cardiac function and structure and recommendations for grading severity: the Healthy Hearts Consortium.

Abstract

Introduction: Cardiovascular magnetic resonance (CMR) imaging offers precise quantification of cardiac structure and function. However, its clinical utility is often limited by the absence of robust, standardized reference ranges and severity grading thresholds. Aim(s): The aim of this study was to establish age-, sex-, and ethnicity-specific reference ranges and severity grading criteria for CMR-derived ventricular and atrial parameters in healthy adults, accounting for variations between two post-processing software tools. Methods and Results: We analyzed CMR scans from the Healthy Hearts Consortium (HHC), which includes six multi-ethnic international cohorts. Images were automatically segmented using cvi42 (Circle Cardiovascular Imaging) and suiteHEART (Neosoft), with visual and statistical quality control. Ventricular and atrial volumes, myocardial mass, and ejection fractions were derived using short- and long-axis protocols; parameters were indexed to body surface area and height. We defined reference ranges as normal up to the 95% of the prediction interval (PI), and abnormalities as mild up to 99.73%, moderate at 99.73%, and severe at 99.99%, respectively. The final dataset included 4,624 women (51.0%) and 4,435 men (49.0%), with a mean age of 61 +/- 13 years (range 18-83), and a multi-ethnic population (81.6% White, 5.6% South Asian, 5.3% Mixed/Other, 3.8% Black, 3.7% Chinese). Minor systematic differences were observed between cvi42 and suiteHEART, particularly in atrial parameters. Conclusion(s): Our work provides an evidence-based framework for CMR severity grading, offering age-, sex-, and ethnicity-stratified thresholds for mild, moderate, and severe deviations from the reference. These reference values support improved diagnostic accuracy, better risk stratification, and enhanced comparability of CMR findings worldwide. Copyright The copyright holder for this preprint is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC 4.0 International license.