Echocardiography
Transthoracic echocardiography was performed using commercially
available General Electric systems (VIVID Q, S6 or Vivid 7, GE Vingmed
Ultrasound AS, Horten, Norway). Apical long axis, 4-chamber and
2-chamber views were digitally recorded at a frame rate of
>40 fps for offline 2DLS analysis. Standard
echocardiographic findings, but not 2DLS findings, were available to the
attending physician.
An echo study was performed within 24h of the patients’ last chest pain
episode. Patients with suboptimal 2D echo image quality, defined as ≥2
technically suboptimal segments from apical views, were excluded from
the study. All echocardiograms were analyzed in a core lab (Lady Davis
Carmel Medical Center) by a single experienced sonographer (IA) blinded
to all clinical data. Of the 700 patients initially enrolled in the
2DSPER study 48 (6.9%) did not meet the 2D echo image quality criteria
and were withdrawn from the study after the initial core lab analysis.
The final cohort included 605 patients who had complete clinical and
echocardiographic data, including adequate 2DLS analysis. In all 605
patients included, tracking in all LV segments was feasible according to
the 2DLS analysis software.
All 605 echocardiograms included in the final 2DSPER study cohort were
reviewed by a second experienced sonographer (MG) blinded to all
clinical and 2DLS data. Studies with the best image quality, defined as
optimal visualization of all left ventricular segments throughout the
cardiac cycle in all 3 apical views, were classified by the blinded
sonographer as high quality, and the rest as low
quality.22
All echocardiograms were analyzed using a dedicated 2DLS software
(EchoPAC SW version 113.0.3; GE Vingmed Ultrasound AS). For each patient
GLS was computed by averaging all 18 segments. Reproducibility of GLS
measurements in the 2DSPER study has been previously
reported.15