Morphological Determinants of Obstructive Hypertrophic Cardiomyopathy Obtained Using Echocardiography

Abstract

SummaryThe morphological determinants of left ventricular outflow tract (LVOT) obstruction in hypertrophic cardiomyopathy (HCM) are not completely understood. We aimed to identify the anatomical risks of the obstruction using echocardiography.Fifty patients with untreated HCM were classified into two groups: those with LVOT pressure gradient (LVOTPG) !30 mmHg (obstructive HCM [HOCM] group) and those with LVOTPG < 30 mmHg (HNCM group). The echocardiographic morphological variables were analyzed to determine whether they were predictive of LVOT obstruction. Systolic anterior motions of the mitral valve were observed in 100% of patients in the HOCM group but only in 58% in the HNCM group. There were no significant differences in wall thickness, end-systolic LV dimension (LVDs), or LVOT diameter between the two groups. However, HOCM subjects had a shorter distance from papillary muscles to the inter-ventricular septum (5.97 ± 2.3 versus 9.20 ± 1.9 mm, respectively, P < 0.0001) and a longer anterior mitral leaflet (AML) length (24.7 ± 5.8 versus 20.1 ± 5.4 mm, respectively, P < 0.01) compared to the HNCM group. The AML length/LVDs ratio was significantly higher in the HOCM group compared to the HNCM group (1.02 ± 0.34 versus 0.78 ± 0.26, P < 0.01), and an LVOT obstruction was predicted with an area under the curve of 0.71 (P < 0.05). Multiple linear regression revealed that only the AML length/LVDs ratio was independently associated with LVOTPG (P < 0.01).The AML length/LVDs ratio has a significant predictive value for LVOT obstruction and a strong relationship with LVOTPGs. The AML length/LVDs ratio determines the anatomical risk of LVOT obstruction in HCM.(Int Heart J Advance Publication)

Machine learning evaluation of LV outflow obstruction in hypertrophic cardiomyopathy using three-chamber cardiovascular magnetic resonance

“…The result is a drop in pressure, known as the Venturi effect [ 31 ], which causes the AML to be pulled anteriorly into the LVOT. Given the ability of SAM to predict obstruction in HCM as demonstrated by Nara et al [ 18 ], this may explain why our results indicate AML anatomy metrics are highly predictive of LVOTO, despite relatively poor identification performance.…”

“…Moreover, studies using three-dimensional transoesophageal echocardiography and multidetector computed tomography have suggested that the LVOT is elliptical in shape, not round [ 33 ]. Therefore, the 2D LAX view may result in the underestimation of the LVOT diameter as it does not always portray the longest span of the outflow tract, thus this may have introduced a systematic error in these measurements [ 18 ].…”

“…Finally, studies have identified SAM of the MV as a significant morphological determinant of LVOTO [ 18 ], which is conventionally detected using echocardiography [ 15 ] as it is not directly measurable using CMR. Thus, it was not feasible to incorporate direct assessment of SAM into our SOP.…”

“…CMR may also provide useful information on the mechanisms of LVOTO, which are thought to include three main contributions: (i) LV hypertrophy, including basal septal thickness, (ii) mitral valve interplay, including its systolic anterior motion (SAM) and and/or elongation of the anterior mitral leaflet (AML), and (iii) LV chamber morphology, including anterior displacement of the papillary muscles [ 15 – 18 ].…”

Correlations between cardiac troponin I and nonsustained ventricular tachycardia in hypertrophic obstructive cardiomyopathy

“…LVOT obstruction is a hallmark of more severe symptoms and worse prognosis in patients with HCM 16,17 . Previous studies indicated that circulating biomarkers representing myocardial injury (cardiac troponin I, cTnI), cardiac function (N‐terminal pro‐brain natriuretic peptide, NT‐pro BNP), and inflammation (high sensitivity C‐reactive protein, hs‐CRP) played important roles in predicting adverse outcomes in HCM patients 18‐20 .…”