Microvascular obstruction (MVO) and transmural infarct size are prognostic factors after acute myocardial infarction (AMI). We assessed the value of myocardial deformation patterns using 3D speckle tracking imaging (3DSTI) in detecting myocardial and microvascular damage after AMI. One hundred patients with first ST-segment elevation MI from the REMI Study were prospectively included. Transthoracic echocardiography with 3DSTI and CMR were performed within 72 h after revascularization therapy. Global (3DG) and segmental (3DS) values of LV longitudinal (LS), circumferential and radial area strain were obtained. Late gadolinium enhancement (LGE) and MVO was quantified as transmural (>50%) or non-transmural (<50%). Predictive performance was assessed by area under the receiver operating curve characteristic (AUC). Mean LVEFCMR was 45.8 ± 9.2 % with 22.2 ± 12.7% transmural LGE. MVO was present in 55 patients (MVO transmural extent 11.4 ± 11.8%). In global analysis, all 3DG strain values were correlated with LVEFCMR and infarct size, with the best correlation obtained for 3DGAS (r = -0.678; p < 0.0001). All 3DG strain values, with the exception of LS, were significantly different between patients with and without MVO. In segmental analysis, all 3DS strain values were significantly lower in transmurally infarcted segments than in non-infarcted segments, and all 3DS values except 3DSRS were significantly lower in non-transmural infarcted segments than in non-infarcted segments. The best 3DS strain for detecting non-viable segments with MVO (MVO > 75%) was 3DSAS [AUC 0.867 (0.849-0.884), 78.0% sensitivity and 81.1% specificity for 3DSAS = -16.1%]. Importantly, 3DSRS and 3DSAS were associated with an increase in diagnostic accuracy of both transmural LGE and MVO over 3DSLS (all increase in AUC > 0.04, all p < 0.01). The newly developed 3DSTI, especially 3DSAS, is a sensitive and reproducible tool to predict and quantify the transmural extent of scar. This new early imaging strategy improve the prediction of MVO while enabling to assess the success of reperfusion and the risk of late systolic remodeling in STEMI.