Cardiac magnetic resonance assessment of mitral annular disjunction in children: insights from T1 mapping and feature-tracking strain analysis

Abstract

Background: Mitral annular disjunction is an increasingly recognized structural abnormality associated with myocardial remodeling. While related functional and structural alterations have been well documented in adults, data on pediatric mitral annular disjunction remain scarce.

Objective: To assess early myocardial structural and functional changes in pediatric patients with mitral annular disjunction using cardiac magnetic resonance (CMR) feature-tracking strain and parametric mapping.

Materials and methods: In this retrospective study, 32 pediatric patients with mitral annular disjunction confirmed by CMR and 16 age- and sex-matched controls with normal CMR findings were included. Cine imaging, late gadolinium enhancement, native T1 mapping, extracellular volume, and CMR strain analysis were performed. Holter monitoring data were evaluated for ventricular ectopy.

Results: Patients with mitral annular disjunction demonstrated significantly reduced global, mean basal, and segmental basal radial, circumferential, longitudinal strain values compared to controls. Also, native T1 and extracellular volume were significantly higher in the mitral annular disjunction group. Late gadolinium enhancement was present in 21.9% of patients with mitral annular disjunction. Ventricular ectopy was observed in 48.3%, with no significant association with late gadolinium enhancement. Subgroup analysis showed longer mitral annular disjunction distances, more frequent systolic curling, late gadolinium enhancement, and ventricular ectopy in patients with mitral annular disjunction and mitral valve prolapse, compared to those with isolated mitral annular disjunction.

Conclusion: Pediatric mitral annular disjunction is associated with early myocardial alterations, including impaired deformation, elevated native T1, and extracellular volume. These findings suggest that subclinical myocardial remodeling may begin in childhood, and CMR is valuable in detecting these subtle changes.

Keywords: Cardiac imaging techniques; Children; Magnetic resonance imaging; Mitral valve.