Impact of hypertrophic pattern and obstruction on cardiovascular magnetic resonance myocardial strain and left atrioventricular coupling in hypertrophic cardiomyopathy: a retrospective study.

BACKGROUND

Hypertrophic cardiomyopathy (HCM) exhibits complex phenotypic heterogeneity. Left ventricular myocardial strain and atrioventricular coupling hold significant clinical value in cardiovascular diseases; however, the impact of different left ventricular hypertrophy (LVH) distribution patterns on myocardial strain and atrioventricular coupling remains unclear in HCM.

OBJECTIVE

To investigate left ventricular strain and left atrioventricular coupling in HCM patients with different LVH distribution patterns and obstruction using cardiac magnetic resonance feature tracking.

METHODS

A total of 199 HCM patients were divided into four LVH patterns (P1-P4): P1 (isolated septal hypertrophy), P2 (septal+other segments hypertrophy, non-apical), P3 (apical+other segments hypertrophy) and P4 (isolated apical hypertrophy). We measured left ventricular global longitudinal strain (LVGLS), global radial strain (LVGRS), global circumferential strain (LVGCS) and left atrioventricular coupling index (LACI). Parameters were compared across groups and between obstructive HCM (HOCM) and non-obstructive HCM (HNCM).

RESULTS

Strain differed significantly among the four groups (all p<0.05). LVGLS impairment was most severe in P2. P4 showed better LVGRS and LVGCS than the other groups. Absolute LVGRS and LVGCS were higher in HOCM than HNCM (both p<0.05), but LVGLS did not differ. However, after indexing LVGRS to left ventricular maximal wall thickness (LVMWT) (LVGRS/LVMWT), the difference between HOCM and HNCM was no longer significant (p=0.999). HOCM also had higher LACI, left atrial volumes (all p<0.05). On multivariable analysis, P2 was independently associated with LVGLS impairment (β=2.14, adjusted p=0.007). P4 was independently associated with better LVGRS and LVGCS (adjusted p<0.05). Obstruction was independently associated with LVGCS (adjusted p<0.05). LACI showed no independent association with hypertrophy pattern or obstruction (all adjusted p>0.05).

CONCLUSION

LVH patterns on cardiac MR effectively differentiate myocardial strain in HCM. P2 identifies a subtype with severe LVGLS impairment, whereas P4 shows preserved LVGRS and LVGCS. Obstruction independently correlates with compensatory enhancement of LVGCS with larger left atrial volumes, whereas the augmentation of LVGRS may be attributable to wall thickness differences. LACI is not independently associated with LVH pattern or obstruction.