Analysis of structural and anatomical features of the mitral valve using computed tomography and magnetic resonance imaging in hypertrophic cardiomyopathy

Introduction: hypertrophic cardiomyopathy (HCM) is a common inherited myocardial disorder. In a significant proportion of patients with obstructive HCM, abnormalities of the papillary muscles (PM) are a key contributor to dynamic left ventricular outflow tract (LVOT) obstruction, beyond septal hypertrophy alone. Surgical papillary muscle reorientation is a targeted method for correcting this pathology.
Aim: to perform a comprehensive analysis of the structural and anatomical features of the mitral valve (MV) and subvalvular apparatus using cardiac CTA and MRI in patients with obstructive HCM to identify candidates for PM reorientation and to compare their characteristics and short-term outcomes with patients undergoing standard surgical procedures.
Materials and Methods: a prospective single-center study included 102 patients with obstructive HCM, divided into groups: Group 1 (n=75/102) – patients undergoing isolated myectomy; within this group, a subgroup, Group 2 (n=19/75) underwent concomitant PM reorientation in addition to myectomy; Group 3 (n=27/102) – patients undergoing myectomy with MV repair/replacement. All patients underwent preoperative evaluation, including echocardiography, CTA, and MRI, to assess MV, PM, and subvalvular apparatus morphology.
Results: patients in Group 2 were characterized by significantly lower basal septal thickness (1.6 ± 0.3 cm vs. 2.1 ± 0.4 cm; p<0.001), the presence of bifid PMs (100% vs. 21.7–38.5%; p<0.001), and a greater anterolateral PM mobility angle (14.5° ± 2.0° vs. 9.5° ± 2.5°; p<0.001). ROC analysis showed high predictive value for an anterolateral PM mobility angle >12.5° (AUC=0.891) and the presence of bifid PMs (AUC=0.892) in selecting candidates for reorientation. The combination of these features provided a sensitivity of 95.5% and specificity of 88.5%. Postoperatively, the reorientation group achieved the lowest LVOT gradient (9.5 ± 6.3 mm Hg vs. 15.2 ± 8.5; p=0.004) with no need for permanent pacemaker implantation (0% vs. 11.2%; p<0.05).
Conclusions: multimodal imaging identifies a specific phenotype of obstructive HCM where PM abnormalities are the primary substrate for LVOT obstruction. PM reorientation is an effective and safe surgical treatment for selected patients, relieving obstruction with a low risk of complications.

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