The role of contrast-enhanced (ce) cardiac magnetic resonance in risk stratification of patients with depressed left ventricle (LV) function is widely studied. In this study, we investigated the myocardial infarct size and characteristics by ce-magnetic resonance imaging (MRI) and its relationship with spontaneous ventricular arrhythmia occurrence during follow-up of in patients with mild LV systolic dysfunction and nonsustained ventricular tachycardia (VT).This study enrolled 32 patients with postmyocardial infarction with an LV ejection fraction between 40% and 50% and nonsustained VT. Cardiac MRI performed to identify cardiac scar size and characteristics. Dense scar, peri-infarction zone and total infarct masses were calculated, these values to LV mass ratios were obtained. All patients were followed up 48 ± 6 months. Cardiac magnetic resonance data compared among patients with (n = 6) and without spontaneous sustained VT (n = 26).During follow-up, 6 patients experienced sustained VT (VT+ group), whereas 26 patients had no sustained ventricular arrhythmia (VT- group). The groups had similar baseline clinical characteristics. The LV masses, volumes and ejection fractions did not differ significantly between 2 groups. For the VT+ group versus VT- group dense scar to LV mass were similar (3.1 ± 0.3% versus 3.3 ± 0.9%, P = not significant). Ratio of peri-infarction zone to LV mass (30.9 ± 6.1% versus 21.3 ± 7.5%, P = 0.007) and total infarct to LV mass (34.1 ± 6.1% versus 24.6 ± 7.9%, P = 0.011) were larger in patients with sustained VT.This small study supports the potential utility of ce-MRI to identify patients with postmyocardial infarction prone to develop serious ventricular arrhythmias.