Assessment of left ventricular function in ST-elevation myocardial infarction by global longitudinal strain: a comparison with ejection fraction, infarct size, and wall motion score index measured by non-invasive imaging modalities

Aims We aimed to compare two-dimensional global longitudinal strain (GS) with different non-invasive imaging modalities for the assessment of left ventricular function in an ST-elevation myocardial infarction population. Methods and results GS was compared with ejection fraction (EF) determined by magnetic resonance imaging (MRI), standard echocardiography (echo), contrast echo, and electrocardiography-gated single-photon emission computed tomography (SPECT), as well as with MRI-determined relative infarct size and echo-determined wall motion score index (WMSI), in 163 patients participating in the NORwegian Study on District Treatment of ST-Elevation Myocardial Infarction (NORDISTEMI). The linear relation between GS and standard echo (r(2) = 0.43, P < 0.001), contrast echo (r(2) = 0.38, P < 0.001), and SPECT-determined EF (r(2) = 0.52, P < 0.001) was almost identical as that between GS and the gold standard MRI-determined EF (r(2) = 0.47, P < 0.001). GS was best associated with WMSI by echo (r(2) = 0.55, P < 0.001), while the associations between GS and relative infarct size were weaker (r = 0.43, P < 0.001). Receiver operator characteristics curves, used to analyse the ability of GS to discriminate low EF (<= 40%) measured by the four different modalities, large myocardial infarction (MI >= 15.7%), and high WMSI (>= 1.5), were significant for all. GS was shown to be the best predictor of low EF measured by MRI [area under the curve (AUC) 0.965], while the lowest AUC was found between GS and large MI (0.814). Conclusion Global strain is associated well with EF measured by all modalities. Global strain was found to be the best predictor of low EF measured by the gold standard MRI. Since global strain is an inexpensive test, these data may be of health economic interest.