Changes in components of left ventricular mechanics under selective beta-1 blockade: insight from traditional and new technologies in echocardiography

Abstract

Aims: Myocardial inotropism is considered to be reduced under beta-1 adrenoreceptor blockage (beta1-block). However, relationships between components of left ventricular (LV) systolic mechanics under beta1-block accounting for physiological correlates are only partially explored.

Methods and results: Hypertensive outpatient without previous cardiovascular events and with normal LV ejection fraction (EF) at rest underwent echocardiographic evaluations of LV size and systolic function by standard, tissue-Doppler, and speckle-tracking methods before and after 2 weeks of treatment with bisoprolol to obtain change in LV systolic mechanics at a stable heart rate reduction (-20 +/- 10% from baseline) without significant change in LV mass. In the study sample (n = 26, 62% women, mean age 52 +/- 10 years), under bisoprolol, afterload [i.e. circumferential (CESS) and meridional (MESS) end-systolic stress], LV mass, left atrial volume, and EF did not change significantly; LV chamber contractility [i.e. CESS/LV end-systolic volume index (CESS/ESVi) as well as MESS/ESVi] and relative wall thickness (RWT) decreased; stroke volume increased (all P < 0.05). Circumferential LV contractility (i.e. stress-corrected midwall shortening) increased, whereas regional longitudinal strain and strain rate, and global longitudinal strain decreased (all P < 0.05). Peak velocities of the systolic displacement of the lateral and medial mitral anulus did not change under bisoprolol. Parameters of longitudinal LV systolic function did not correlate with preload, afterload, RWT, or with stoke volume.

Conclusion: In hypertensive subjects with preserved LV EF, parameters of longitudinal LV systolic mechanics may not reflect the LV myocardial contractility status in steady-state conditions under short-term treatment with beta1-block.