Segmental Strain and Strain-Rate Imaging to Assess Cardiac Function in Patients With Limb-Girdle Muscular Dystrophy R9: An Observational Study of the Norwegian LGMDR9 Cohort

Purpose

Cardiomyopathy is a prevalent feature of limb-girdle muscular dystrophy R9 (LGMDR9), but its characterization remains incomplete. This study aims to assess cardiac function in patients with LGMDR9 using global and segmental myocardial function imaging.

Methods

A total of 42 participants (aged 23–71 years) from the Norwegian LGMDR9 cohort were compared with 97 controls (aged 40–69 years) from the Tromsø Study. Conventional and speckle tracking echocardiography were performed to assess cardiac function. Statistical analyses were adjusted for age and sex.

Results

Patients with LGMDR9 had significantly reduced left ventricular ejection fraction (LVEF: 52.2% vs. 57.0%, p < 0.001) and decreased absolute global longitudinal strain (GLS: 17.6% vs. 20.5%, p < 0.001). Systolic dysfunction in patients was further observed by increased end-systolic left ventricular volume and internal diameter. Diastolic dysfunction was evident with reduced early to late ventricular filling velocities and further verified by decreased longitudinal strain-rate during early diastole (SR-E) and increased longitudinal strain-rate during atrial contraction (SR-A). Importantly, segmental analysis revealed region-specific differences in strain and strain-rate; mid and apical segments had decreased absolute strain, while basal segments remained largely unaffected. Notably, patients with normal LVEF also displayed decreased GLS (18.7% vs. 20.6%, p < 0.001) and regional and segmental alterations in strain and strain-rate.

Conclusion

We demonstrate that patients with LGMDR9 exhibit both systolic and diastolic dysfunction, primarily affecting the mid and apical myocardial segments. Strain and strain-rate imaging may serve as sensitive tools for early detection of myocardial dysfunction, and support clinical management and interventional studies in LGMDR9.