2025/08 - Cardiac Phenotype Characterization at MRI in ALPK3 Associated Hypertrophic Cardiomyopathy [Journal Club]-Joint image reconstruction and segmentation of real-time cardiovascular magnetic resonance imaging in free breathing using a model based on disentangled representation learning

Joint image reconstruction and segmentation of real-time cardiovascular magnetic resonance imaging in free breathing using a model based on disentangled representation learning

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Video Summary

This JCMR Journal Club episode featured a study from Sichuan University on the cardiac MRI phenotype of adults with ALPK3-associated hypertrophic cardiomyopathy (HCM). The presenters explained that ALPK3 is an increasingly recognized non-sarcomeric gene linked to HCM, especially in Asian populations, but its imaging phenotype is still not well defined.<br /><br />In a single-center Chinese cohort of 575 HCM patients, 37 carried ALPK3 variants. The study found that ALPK3 carriers were more likely than sarcomere-gene-positive patients to show apical HCM, especially mixed apical hypertrophy, and generally had a lower left ventricular wall thickness and less late gadolinium enhancement (LGE), suggesting a lower fibrosis burden. No major imaging differences were seen between ALPK3 truncating and missense variants. T1 mapping and ECV were elevated in representative cases, while T2 mapping did not differ significantly.<br /><br />The discussion highlighted methodological issues such as contrast agent choice, T1 mapping sequence details, and LGE quantification methods, as well as the need to study genotype-positive, phenotype-negative relatives and pediatric patients. The session concluded that ALPK3 may define a distinct HCM subtype with apical predominance and a characteristic fibrosis pattern, but larger multicenter studies are needed.

Keywords

ALPK3

hypertrophic cardiomyopathy

cardiac MRI

apical HCM

late gadolinium enhancement

fibrosis

T1 mapping

ECV

Chinese cohort