OVERVIEW

Mitral geometry on the Mechanism of Left Ventricular Outflow Tract Obstruction in Hypertrophic Cardiomyopathy is organized by American Society of Echocardiography (ASE).

Release Date: August 1, 2024
Expiration Date: August 1, 2025

Description:
Hypertrophic cardiomyopathy (HCM) is a complex inherited cardiomyopathy due to sarcomere protein gene mutations, with an estimated prevalence ranging from 1:500 to as high as 1:200.1 The pathologic manifestations of symptomatic HCM are often attributable to left ventricular outflow tract obstruction (LVOTO), left ventricular (LV) diastolic dysfunction, and mitral regurgitation (MR). Patients with LVOTO may be at increased risk of developing arrhythmias, stroke, heart failure, or sudden cardiac death.2,3 Extended transaortic septal myectomy is the gold standard for the treatment of patients with symptomatic hypertrophic obstructive cardiomyopathy (HOCM).4 Given that LVOTO is a complex entity arising from various phenotypes of LV hypertrophy (LVH) and mitral valve (MV) apparatus abnormalities, understanding the mechanisms of LVOTO plays a crucial role in surgical management and clinical care.

In patients with obstructive HCM without overt LVH, redundant MV leaflets, aberrant muscle bundles or chordal attachments, and hypermobile bifid papillary muscle are often associated with dynamic LVOTO and may require additional surgical intervention.5, 6, 7 However, the impact of MV geometry on the mechanism of LVOTO in HCM has not been fully explored. The aortomitral angle is the angle between the mitral annular plane and the aortic annular plane and is a known predictor of the likelihood of MV systolic anterior motion (SAM) after MV repair.8 To our knowledge, this is the first study to consider the assessment of MV geometry, rather than septal hypertrophy, as a more important component in LVOTO. The primary objective of the present study is to determine which MV geometry is an independent predictor of obstruction in HCM.

Learning Objectives:

Identify the mechanism of left ventricular outflow tract obstruction in HCM
Consider how the aorto-mitral angle and leaflet length generate SAM and outflow obstruction
Recognize the aspects of mitral geometry that are important predictors of SAM and LVOTO independent of septal hypertrophy
Use echocardiography to distinguish between LVOTO caused by septal hypertrophy and obstruction caused by structural abnormalities of the mitral valve regardless of hypertrophy
Effect echocardiographic protocols to provide comprehensive assessment of the mitral valve apparatus.