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Background: Left ventricular (LV) dyssynchrony is very important in clinical cardiology and is related mainly to electrical conduction delay. However, there are limited results about mechanical dyssynchrony after myocardial infarction (MI) in patients without QRS prolongation. Purpose: The aim of this study was to evaluate the presence of dyssynchrony in the chronic phase of MI in patients with narrow QRS-complex using 2D Speckle Tracking echocardiography.Methods: 25 patients with myocardial infarction and 27 age-matched controls were examined with conventional and 2D Speckle Tracking echocardiography. All patients had a normal duration of QRS-complex. Peak systolic radial strain (RS) and circumferential strain (CS) on the basal and middle short axis LV level and longitudinal strain (LS) from 4-chamber apical view were measured using a Philips iE33 ultrasound system. Dyssynchrony was assessed by standard deviation (SD) of time from R-wave on ECG to peak systolic RS and CS in all 12, 6 basal and 6 mid segments and SD of time to peak LS in 6 segments.Results: Patients with MI had lower peak systolic RS at mid level (18.7±7.5% vs. 27.5±9.5%, p=0.01), global CS (-11.9 ±3.8% vs. -16.8±3.2%, p<0.0001) and LS (-9.7±3.7% vs. -12.1±6.3%, p=0.001), compared to controls. They had significantly prolonged SD of time to peak RS in 12 segments (84.2±28.3 ms vs. 68.5±27.8 ms, p=0.05) and in 6 mid segments (84.0±27.6 ms vs. 50.4±18.4 ms, p<0.0001), SD of time to peak CS in 12 segments (84.2±41.0 ms vs. 68.4±30 ms, p=0.05) and SD of time to peak LS in 6 segments (129.4±59.3 ms vs. 77.9±42.3 ms, p=0.001). No statistically significant differences in dyssynchrony were registered between patients with anterior and inferior MI, as well as between basal and mid levels neither of MI group, nor controls.Conclusions: MI alters significantly and in long term LV synchronicity, irrespective of narrow QRS-complex.