CMR-Derived Strain and Torsion Reveal Subclinical Dysfunction in Hypertrophic Cardiomyopathy: A Prospective Case–Control Study

<b>Background</b>: Hypertrophic cardiomyopathy (HCM) is frequently associated with preserved left ventricular ejection fraction (LVEF), yet subclinical myocardial dysfunction often escapes detection using conventional imaging. Cardiac magnetic resonance (CMR) with feature tracking (FT) enables precise assessment of myocardial deformation and mechanics. <b>Methods</b>: In this prospective case-control study, we evaluated 150 HCM patients and 100 age- and sex-matched healthy controls using standardized CMR protocols. Global longitudinal strain (GLS), circumferential strain (GCS), radial strain (GRS), and left ventricular (LV) torsion were quantified via FT-CMR. Myocardial fibrosis was assessed through late gadolinium enhancement (LGE), native T1 mapping, and extracellular volume (ECV). <b>Results</b>: HCM patients showed significantly impaired strain and torsion metrics compared with controls: GLS (-16% vs. -20%), GCS (-18% vs. -21%), GRS (29% vs. 38%), and global LV torsion (1.27°/cm vs. 1.95°/cm), all <i>p</i> < 0.001. These abnormalities were also observed in LGE-negative patients, suggesting early functional remodeling. Global LV torsion demonstrated the highest diagnostic performance for LGE detection (AUC = 0.995), surpassing those of GLS (0.877), native T1 (0.731), and ECV (0.657). A cut-off value of 0.7°/cm provided optimal sensitivity and specificity, and was associated with adverse prognosis in survival analysis. <b>Conclusions</b>: CMR-derived strain and torsion parameters detect early myocardial dysfunction in HCM beyond conventional markers. Global LV torsion, in particular, emerges as a sensitive and robust non-invasive marker with diagnostic and prognostic potential.