Distinguishing ventricular septal bulge versus hypertrophic cardiomyopathy in the elderly

Abstract

The burgeoning evidence of patients diagnosed with sigmoidal hypertrophic cardiomyopathy (HCM) later in life has revived the quest for distinctive features that may help discriminate it from more benign forms of isolated septal hypertrophy often labelled ventricular septal bulge (VSB). HCM is diagnosed less frequently than VSB at older ages, with a reversed female predominance. Most patients diagnosed with HCM at older ages suffer from hypertension, similar to those with VSB. A positive family history of HCM and/or sudden cardiac death and the presence of exertional symptoms usually support HCM, though they are less likely in older patients with HCM, and poorly investigated in individuals with VSB. A more severe hypertrophy and the presence of left ventricular outflow obstruction are considered diagnostic of HCM, though stress echocardiography has not been consistently used in VSB. Mitral annulus calcification is very prevalent in both conditions, whereas a restrictive filling pattern is found in a minority of older patients with HCM. Genetic testing has low applicability in this differential diagnosis at the current time, given that a causative mutation is found in less than 10% of elderly patients with suspected HCM. Emerging imaging modalities that allow non-invasive detection of myocardial fibrosis and disarray may help, but have not been fully investigated. Nonetheless, there remains a considerable morphological overlap between the two conditions. Comprehensive studies, particularly imaging based, are warranted to offer a more evidence-based approach to elderly patients with focal septal thickening.

Ventricular Arrhythmia in Septal and Apical Hypertrophic Cardiomyopathy: The French-Canadian Experience

“…True sHCM is typically characterized by reverse curve septal hypertrophy representing the majority of sHCM cases in our study. This phenotype should be distinguished from isolated sigmoid hypertrophy of the basal septum, which represents a more benign form and is often no true primary HCM (51).…”

Right ventricular basal inflow and outflow tract diameters overestimate right ventricular size in subjects with sigmoid-shaped interventricular septum: a study using three-dimensional echocardiography

“…A sigmoid septum (also denoted as ventricular septal bulge or angled aorta) is considered a normal variant or a minor abnormality often encountered in echocardiographic examinations of the elderly [12][13][14][15]23]. Sometimes, distinguishing between the SS and hypertrophic cardiomyopathy can be problematic because SS can cause an LV outflow tract obstruction [24][25][26][27][28]. It has been also reported that subjects with SS more frequently have hypertension, greater relative wall thickness, and LV diastolic dysfunction [15,23,30].…”

The evolution of basal septal hypertrophy: From benign and age‐related normal variant to potentially obstructive and symptomatic cardiomyopathy

“…A recent review suggests an algorithm for differentiating what the authors term “ventricular septal bulge” (VSB) from HCM. The proposed entry criteria are BSH>1.2 cm and ratio of basal to mid‐septal thickness ≥1.5 cm.…”