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.