Determinants of echocardiographic 2D speckle tracking left ventricular global longitudinal strain and differences between peak systolic and maximum strain in identifying reduced systolic function

Abstract

Purpose: Echocardiographic 2D speckle tracking left ventricular (LV) global longitudinal strain (GLS, %) has been proposed as an index of LV systolic function and a possible substitute of biplane ejection fraction (EFb, %), given its semi-automatic calculation modality. Peak systolic GLS (GLPS) is calculated online, but maximum GLS (GLMS, which includes post-ejection strain) offline. Aim of this study was to analyse determinants of and differences between GLPS and GLMS in identifying EFb< 50% in unselected patients. Methods: We studied 300 consecutive patients with (203) and without (97) heart diseases undergoing echocardiography (ranges, age: 14-93 y., HR: 40-130 bpm, systolic arterial pressure: 90-180 mmHg, EFb: 15-78%), using a GE Vivid7 system and offline analysis on Echopac v12. GLPS and GLMS were derived by LV wall tracking in the 3 apical views. Low normal cutoffs for GLPS and GLMS were set respectively at -17% and -18% (based on lower 5% percentile of 60 previously screened normal subjects). Results: GLPS and GLMS correlated highly (r=0.92, p<0.001). At multiple regression analysis, LV end-diastolic volume index, relaxation (tissue Doppler Ea) and stroke index (LV outflow pulsed Doppler) similarly determined GLPS (r=0.87, p<0.001) and GLMS (r=0.88, p<0.001); the former was also influenced by LV myocardial performance index (contractility), filling pressure (tissue Doppler E/Ea) and mass index. Relaxation did not influence EFb. For both GLPS and GLMS, feasibility and accuracy were high and negative (NPV) was superior to positive (PPV) predictive value in identifying EFb <50% (Table). Compared to patients with normal EFb and GLPS, those with reduced GLPS but normal EFb were characterized by concentric LV hypertrophy (p<0.001) and prolonged relaxation (p=0.002). View this table: Identification of EFb (feasibility = 100% Conclusions: Both GLPS and GLMS are highly feasible and accurate in identifying reduced EFb in unselected patients. Given similar physiopathologic determinants, the online modality of the former makes it a preferred modality to evaluate global LV systolic function, with the added value of identifying patients with normal EFb and diastolic (prolonged relaxation) dysfunction.