Evaluation of diastolic function in hypertrophic cardiomyopathy and cardiac amyloidosis through semi-automatic assessment – a multi-center, multi-vendor cardiovascular magnetic resonance study

BACKGROUND AND AIMS: Unlike systolic heart function, the assessment of diastolic heart function is often demanding using cardiovascular magnetic resonance (CMR) imaging. This study aims to assess the value of semi-automatic CMR-derived biplane functional parameters in patients with cardiac light chain (AL) and transthyretin (ATTR) amyloidosis or hypertrophic cardiomyopathy (HCM). METHODS: This retrospective, multi-center, multi-vendor study included patients with a diagnosis of HCM or cardiac AL/ATTR amyloidosis. Proven healthy volunteers served as controls. CMRs were assessed semi-automatically to derive atrial functional parameters (volume, long axis strain, ejection fraction [EF] of both atria) and left and right atrioventricular coupling index (LACI, RACI). Subsequently, group differences after adjustment for age, sex, left ventricular (LV) EF, body mass index and presence of atrial fibrillation as well as their correlation with N-terminal pro-B-type natriuretic peptide (NT-proBNP) and New York Heart Association (NYHA) class were calculated. RESULTS: A total of 400 participants were included (94 HCM, 95 AL, 116 ATTR, 95 controls; mean age 58 ± 15 years, 67% male (269/400)). Semi-automated analysis was feasible in all cases (median duration 34 s) with excellent reproducibility. Compared with controls, patients revealed markedly higher LACI values (40.1% vs. 15.2%, p<0.001) and impaired LA function (EF 34.3% vs. 65.2%, strain 11.5% vs. 41.5%, both p<0.001). RACI and RA function, however, distinguished disease groups: RA indices were preserved in HCM but significantly impaired in amyloidosis (RACI 41.8% vs. 20.4%; RA EF 28.8% vs. 52.5%; RA strain 12.3% vs. 34.4%, p<0.001 for all). After adjustment, both LA volume and LACI showed independent associations with NYHA class and NT-proBNP, with LACI demonstrating the strongest correlations and outperforming LVEF. CONCLUSIONS: Semi-automated biplane CMR enables fast and reproducible assessment of atrial function. Combined analysis of LACI and RACI provides clinically relevant diagnostic differentiation between HCM and cardiac amyloidosis and correlates with patient symptom burden more accurately than LVEF.