Specific deformation pattern in hypertensive patients with septal bulge and preserved systolic function

Abstract

A wide range of subclinical changes in left ventricular (LV) geometry and function can be observed, even in the early course of arterial hypertension (HTN). Aim of the study was to investigate if the appearance of isolated basal septal hypertrophy (BSH, septal bulge) in asymptomatic young and middle-aged adults with HTN could be a marker of incipient LV systolic dysfunction when other measures of global LV function are still normal. A total of 138 patients with primary arterial hypertension, aged less than 65 years, with no comorbidities and with preserved LV ejection fraction (EF) were included. Complete 2D transthoracic echocardiography study was preformed according to standardized protocol, as well as deformation study using speckle tracking echocardiography. Global and regional longitudinal strain was measured in apical 4-, 2- and 3-chamber views according to 18-segments model. Global and regional circumferential and radial strains were measured in short axis view. Average was taken from each of the six basal, middle and apical LV segments. Patients were divided into two groups according to BSH presence and values were compared. Basal septal hypertrophy was found in half of the patients (53.6%). The whole cohort had altogether normal LV global systolic function, as well as global indices of radial strain (GRS 43.86 ± 10.75%) and longitudinal strain (GLS - 19.73 ± 2.19%), while global circumferential strain (GCS) was mildly reduced (GCS - 19.5 ± 2.81%). BSH patients had more expressed LV geometry changes (LV mass: 89.19 ± 24.59 g/m² vs 109.15 ± 25.33 g/m², p < 0.001; relative wall thickness: 0.3 ± 0.08 vs 0.38 ± 0.11, p < 0.001) and also revealed a specific pattern of longitudinal deformation impairment in three LV segments (basal and mid interventricular septum, basal anteroseptum). "Strain gradient" from LV base to apex (basal < mid < apical) was observed in the whole population for longitudinal and circumferential strain, and it was more pronounced in the BSH group. This group had more impaired basal LS, while apical CS was improved. Subendocardial longitudinal strain was also more impaired in the BSH group. This study brings new meaning to basal septal hypertrophy (BSH) occurrence in hypertensive patients with discrete global concentric remodeling. Regional systolic dysfunction of the basal and mid LV segments is found, while apical segments increase in deformation. This specific "strain gradient" pattern was found to be more pronounced in patients with BSH. The recognition of BHS in apparently healthy hypertensive patients with no impairment in global systolic function may suggest latent target organ damage with regional impairment of systolic function and the need to imply more aggressive treatment approach.

Keywords: Arterial hypertension; Basal septal hypertrophy; Circumferential strain; Longitudinal strain; Septal bulge; Speckle tracking echocardiography.