Abstract
Aims: We have previously shown that 2-dimentional strain is not
a useful tool for ruling out acute coronary syndrome (ACS) in the
emergency department (ED). The aim of the present study was to determine
whether in patients with suspected ACS, global longitudinal strain
(GLS), measured in the ED using 2-dimensional strain imaging, can
predict long-term outcome.
Methods: Long-term (median 7.7 years [IQR 6.7-8.2]) major
adverse cardiac events (MACE; cardiac death, ACS, revascularization,
hospitalization for heart failure or atrial fibrillation) and all-cause
mortality data was available in 525/605 patients (87%) enrolled in the
Two-Dimensional Strain for Diagnosing Chest Pain in the Emergency Room
(2DSPER) study. The study prospectively enrolled patients presenting to
the ED with chest pain and suspected ACS but without a diagnostic ECG or
elevated troponin. GLS was computed using echocardiograms performed
within 24 hours of chest pain. MACE of patients with worse GLS
(> median GLS) was compared to patients with better GLS (≤
median GLS).
Results: Median GLS was -18.7%. MACE occurred in 47/261 (18%)
of patients with worse GLS as compared with 45/264 (17%) with better
GLS, adjusted HR 0.87 (95% CI 0.57-1.33, P =0.57). There was no
significant difference in all-cause mortality or individual end-points
between groups. GLS did not predict MACE even in patients with optimal
2-dimensional image quality (n=164, adjusted HR=1.51, 95% CI 0.76-3.0).
Conclusions: GLS did not predict long-term outcome in patients
presenting to the ED with chest pain and suspected ACS, supporting our
findings in the 2DSPER study.
Clinical Trial
Registration— URL:http://.clinicaltrials.gov. Unique identifier:
NCT01163019.
Key Words: Global longitudinal strain, speckle tracking
echocardiography, major adverse cardiac events, long-term outcome, acute
coronary syndrome
Left ventricular (LV) systolic function, routinely assessed by
echocardiography, is an important predictor of patient
outcome.1 Left ventricular ejection fraction (LVEF),
commonly used to assess LV systolic function, is operator dependent, has
significant interobserver variability, and does not necessarily
represent myocardial contractility.2,3 Two-dimensional
longitudinal strain (2DLS) using speckle tracking imaging
echocardiography can be analyzed using an automated, reproducible tool
for the assessment of global and segmental LV
function.4–6 Global longitudinal strain (GLS),
calculated from 18 LV segments, has been shown to correlate well with
pressure-volume loop-derived contractility indices.2GLS has been shown to be an independent predictor of outcome, better
than LVEF, in patients with heart failure, myocardial infarction and
valvular heart disease.7–11
Despite the fact that the use of GLS is recommended by current
guidelines, the recently published SUCCOUR (Strain Surveillance of
Chemotherapy for Improving Cardiovascular Outcomes) study, a prospective
multicenter randomized trial, failed to meet its primary endpoint,
preventing a significant reduction in LVEF at 1 year using a GLS-guided
strategy.12–14 These results emphasize the need for
large prospective studies to evaluate the utility of GLS in routine
clinical practice.
The 2-Dimensional Strain Echocardiography for Diagnosing Chest Pain in
the Emergency Room (2DSPER) study was a multicenter, prospective,
blinded study designed to assess the utility of 2DLS in the assessment
of low to moderate risk patients presenting to the emergency department
(ED) with suspected acute coronary syndrome (ACS).15In that study 2DLS was not found to be a useful tool for ruling out ACS
in the ED, despite the fact that several small studies had reported that
2DLS can accurately detect coronary artery disease (CAD) and identify
patients with ACS.16–21 This discrepancy could be
partly explained by the fact that unlike the other studies, in which
most patients without ACS had normal 2DLS, in 2DSPER many patients
without ACS had abnormal 2DLS. The prognostic significance of abnormal
2DLS in these patients is unclear, and to the best of our knowledge,
there are no studies that assessed the utility of 2DLS for the
prediction of outcome in patients presenting to the ED with chest pain.
The aim of the present study was to determine whether GLS can predict
long-term outcome in patients presenting to the ED with suspected ACS.