Abstract 425: Left Ventricular Geometry is Associated Strongly With Regional Strain Properties in Patients With Hypertrophic Cardiomyopathy: An Old and New Paradigm
[Background]A catenoid shape of the interventricular septum is a unique feature in hypertrophic cardiomyopathy (HCM) and affects septal motion. The impact of catenoid shape on regional myocardial function has not, however, been documented.
[Aim]To examine the relationship between septal catenoid shape and myocardial strain properties.
[Methods]Seventy patients with HCM (age, 63±15 yrs) and 20 age- and sex-matched control subjects (age, 61±8 yrs) were enrolled in this study. Conventional echocardiographic examinations were performed using a Vivid 7 Dimension (GE Healthcare). The curvature (1/R) was determined by drawing a matching curve from the apical 4-chamber view (4CV) and parasternal short axis view (SAX) at end-diastole, using digital software (ImageJ software). The catenoid index (CI) was calculated by the following formula: CI = 1/R(4CV) +1/R(SAX). Longitudinal peak systolic strain (ϵ), peak systolic longitudinal strain rate (SRS) and early diastolic longitudinal strain rate (SRE) were calculated from 4CV and SAX in the septum and lateral wall by the two-dimensional speckle tracking method, using custom software (EchoPacPC: GE Healthcare).
[Results] Septal CI was significantly lower in the HCM group than in the control group (0.24±0.14 vs. 0.43±0.12, P<0.01). Septalϵ, SRS and SRE were also significantly lower in the HCM group compared to the control group (−8.8±5.5 vs. −18.7±4.5%, P<0.001, −0.55±0.33 vs. −1.05±0.19 /s, P<0.05, 0.38±0.31 vs. 0.93±0.27 /s, P<0.01, respectively). In the HCM patients, septalϵ was significantly lower than that measured at the lateral wall (−8.8±5.5 vs. −14.5±4.8%, P<0.001). A multivariate model of the HCM patient data that included age, mean blood pressure, LV mass index (LVMI), e′, ratio of interventricular thickness and posterior wall thickness (IVST/PWT), septal CI and LV ejection fraction showed septal CI (β = −0.46, P < 0.0001), IVST/PWT (β = 0.25, P < 0.005) and LVMI (β = 0.23, P < 0.009) were independent predictors (R2 = 0.51) of septalϵ.
[Conclusion] This study showed septalϵ, SRS and SRE are strongly associated with the degree of catenoid index, rather than with septal hypertrophy per sé, indicating a possible link between septal catenoid configuration and regional myocardial function.