Hypertrophy Pattern and Regional Myocardial Mechanics Are Related in Septal and Apical Hypertrophic Cardiomyopathy

Background: Hypertrophic cardiomyopathy (HCM) is associated with considerable phenotypic heterogeneity. Previous studies have shown a relationship between the degree and location of hypertrophy and the prognosis of patients. The aim of this study was to compare left ventricular (LV) circumferential and longitudinal regional mechanics in patients with septal HCM and apical HCM to study the relationship between hypertrophy and function as assessed by myocardial mechanics. Methods: Seventy-two patients with HCM (27 with apical HCM, 45 with septal HCM) were compared with 25 clinically normal and age-matched subjects. Myocardial mechanics were assessed using Velocity Vector Imaging, which extracts myocardial motion estimates from B-mode clips by tracking user-defined points and feature tracking. The Velocity Vector Imaging software generated data on global and regional systolic and diastolic longitudinal and circumferential strain, strain rate, and rotational angle velocities. One-way analysis of variance with post hoc multiple comparisons was used among the three groups. Results: Normal subjects had relatively uniform strain and strain rates for all LV segments. Compared with the normal group, patients with septal HCM had decreased LV regional longitudinal strain rates and strain at both the basal and mid septal and lateral segments (all P < .01). Compared with patients with apical HCM, those with septal HCM had higher LV circumferential strain rates and strain at the basal and mid segments (P < .05 to P < .01). There were significant differences in rotational velocities at the mid segments among the three groups (P < .05 to P < .001). Conclusions: Patients with HCM have abnormalities in myocardial mechanics that are related to the site of abnormal myocardial hypertrophy. (J Am Soc Echocardiogr 2010;23:1081-9.)