Morphology of hypertrophied basal septum contributes to left ventricular outflow tract obstruction in patients with hypertrophic cardiomyopathy: a retrospective case-control study

Jia Tao; Hui Li; Pan Yang; Qinglong Meng; Fujian Duan; Hao Wang

doi:10.21037/qims-22-1034

Morphology of hypertrophied basal septum contributes to left ventricular outflow tract obstruction in patients with hypertrophic cardiomyopathy: a retrospective case-control study

Quant Imaging Med Surg. 2023 Jul 1;13(7):4117-4129. doi: 10.21037/qims-22-1034. Epub 2023 Apr 17.

Authors

Jia Tao¹, Hui Li¹, Pan Yang¹, Qinglong Meng¹, Fujian Duan^{1

2}, Hao Wang¹

Affiliations

¹ Department of Echocardiography, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
² Department of Anesthesiology, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.

Abstract

Background: Detailed assessment of basal septal morphology is essential for understanding the morphological mechanism of left ventricular outflow tract (LVOT) obstruction. We aimed to analyze the morphological alterations of the basal septum (BS) and its surrounding structures and explore their role in LVOT obstruction (LVOTO) in patients with hypertrophic cardiomyopathy (HCM).

Methods: During January 2019 and December 2019, 239 patients were diagnosed with HCM at Fuwai Hospital. We retrospectively reviewed echocardiographic data sets from 105 consecutive patients with HCM [64 with hypertrophic obstructive cardiomyopathy (HOCM) and 41 with hypertrophic non-obstructive cardiomyopathy (HNOCM)] and 28 healthy controls. For quantitatively assessing the basal septal morphology, a novel measurement method was used to obtain the IVSa (the area of the BS protruding into the LVOT), L_A (the largest distance of the BS protruding into the LVOT), L_B (IVSa length in the direction perpendicular to the L_A), and S-IVSa (IVSa divided by L_B). Echocardiographic parameters associated with LVOTO were analyzed using multivariable logistic regression analyses.

Results: There was no significant difference in the maximal basal septal thickness between the HOCM and HNOCM patients (P>0.99). Among the three groups, there were significant differences in the length of the anterior and posterior mitral leaflets (AML and PML), the angle between the mitral valve orifice and ascending aorta (MV-AO) angle, IVSa, L_A, L_B, and S-IVSa (all P<0.001). Compared with HNOCM patients, HOCM patients had significantly longer AML and PML, as well as larger MV-AO angle, IVSa, L_A, and S-IVSa (P<0.001, P<0.001, P<0.001, P=0.002, P<0.001, and P=0.03, respectively). In the multivariate analysis, AML, MV-AO angle, IVSa, and S-IVSa were associated with LVOTO {odds ratio (OR) [95% confidence interval (CI)]: 0.649 (0.462-0.911), P=0.01; 0.842 (0.768-0.923), P<0.001; 1.025 (1.001-1.049), P=0.04; and 0.276 (0.101-0.754), P=0.01, respectively}.

Conclusions: Morphological alterations of the BS relative to the LVOT may provide additional value for estimating the extent of LVOTO. The length of AML, MV-AO angle, IVSa, and S-IVSa were associated with LVOTO.

Keywords: basal septal morphology; echocardiography; hypertrophic cardiomyopathy (HCM); left ventricular outflow tract obstruction.