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

BACKGROUND: 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. METHODS: A computerized search was performed using PubMed, OVID, EMBASE, and Cochrane library databases from inception until 31 July, 2022. Full articles reporting data on LV GLS and LVEF in non-dippers and dippers were considered suitable. RESULTS: 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%, standard means difference [SMD]: 0.73 ± 0.14, confidence interval [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 nighttime systolic BP and myocardial GLS showed a significant, relationship between these variables (coefficient 0.085, P < 0.0001). CONCLUSIONS: 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.