Early Left Ventricular Dysfunction and Non-Dipping: When Ejection Fraction is Not Enough. A Meta-Analysis of Speckle tracking Echocardiography Studies

Abstract

There is evidence that a reduced nocturnal fall in blood pressure (BP) entails an increased risk of hypertensive-mediated organ damage (HMOD) and cardiovascular events. Most studies focusing on left ventricular (LV) systolic function, assessed by conventional LV ejection fraction (LVEF) in non-dippers compared to dippers failed to detect significant differences. To provide a new piece of information on LV systolic dysfunction in the non-dipping setting, we performed a meta-analysis of speckle tracking echocardiography (STE) studies investigating LV global longitudinal strain (GLS), a more sensitive index of LV systolic function. A computerized search was performed using Pub-Med, OVID, EMBASE and Cochrane library databases from inception until July, 31 ^st2022. Full articles reporting data on LV GLS and LVEF in non-dippers and dippers were considered suitable. A total of 648 non-dipper and 530 dipper individuals were included in 9 studies. LV GLS was worse in non-dipper than in their dipper counterparts (-18.4±0.30 vs -20.1±0.23%), SMD: 0.73±0.14, CI: 0.46/1.00, p < 0.0001) whereas this was not the case for LVEF (61.4±0.8 and 62.0±0.8%, respectively), SMD: -0.15±0.09, CI: -0.32/0.03, p=1.01). A meta-regression analysis between night-time systolic BP and myocardial GLS showed a significant, relationship between these variables (coefficient 0.085, p < 0.0001). Our findings suggest that early changes in LV systolic function not detectable by conventional echocardiography in the non-dipping setting can be unmasked by STE; implementation of STE in current practice may improve the detection of HMOD of adverse prognostic significance in individuals with altered circadian BP rhythm.