Multimodality Imaging for Left Ventricular Hypertrophy Severity Grading: A Methodological Review

Abstract

Left ventricular hypertrophy (LVH), defined by an increase in left ventricular mass (LVM), is a common cardiac finding generally caused by an increase in pressure or volume load. Assessing severity of LVH is of great clinical value in terms of prognosis and treatment choices, as LVH severity grades correlate with the risk for presenting cardiovascular events. The three main cardiac parameters for the assessment of LVH are wall thickness, LVM, and LV geometry. Echocardiography, with large availability and low cost, is the technique of choice for their assessment. Consequently, reference values for LVH severity in clinical guidelines are based on this technique. However, cardiac magnetic resonance (CMR) and computed tomography (CT) are increasingly used in clinical practice, providing excellent image quality. Nevertheless, there is no extensive data to support reference values based on these techniques, while comparative studies between the three techniques show different results in wall thickness and LVM measurements. In this paper, we provide an overview of the different methodologies used to assess LVH severity with echocardiography, CMR and CT. We argue that establishing reference values per imaging modality, and possibly indexed to body surface area and classified per gender, ethnicity and age-group, might be essential for the correct classification of LVH severity.

Keywords: Echocardiography; Hypertrophy, left ventricular; Magnetic resonance imaging; Multidetector computed tomography.

Fig. 1. Methodology for the measurement of the septal and posterior wall thickness, LV mass, and LV diastolic diameter with echo, CMR and CT. Short axis: measurements of septal and posterior wall thickness (yellow lines). 2-chamber, 4-chamber, and short axis views: contour drawing of the LV for three-dimensional LVM measurement (blue lines). Contour drawing may primarily be performed in short axis images (all available) and confirmed with long axis views; or, using primarily long axis views while rotating the LV on its longitudinal axis, and confirmed with short axis views (all available). LV (end-)diastolic diameter (green lines). Echo: echocardiography, CT: computed tomography, CMR: cardiac magnetic resonance, LV: left ventricle, LVM: left ventricular mass.

Fig. 2. Calculation of LV mass with an echocardiographic linear method. LV: left ventricle.

Fig. 3. LV geometry patterns. RWT = 2 × posterior wall thickness / LV internal diameter at end diastole. LVMi = LVM / BSA. Normal = green, abnormal = red. Abnormal RWT is defined as > 0.42, abnormal LVMi is > 115 g/m² (men), and > 95 g/m² (women). RWT: relative wall thickness, LVMi: left ventricular mass index, LV: left ventricle, LVM: left ventricular mass, BSA: body surface area.