Background: Left ventricular (LV) enlargement – the main discriminant of postinfarction remodelling – is dynamic and not necessarily progressive. The magnitude of the remodelling process is directly proportional to infarct size (IS), although it is significantly influenced by other factors. Aim: To assess the clinical implications of different patterns of LV volume changes in 1-year echocardiographic follow-up after myocardial infarction (MI) and to determine early predictors of adverse remodelling. Methods: The study group consisted of 132 patients (pts) (mean age 55.7±12 years) with their first MI (STEMI) (67% pts treated with fibrinolysis). In the consecutive ECHO examinations (S1, first day; S2, at discharge; S3, 6 months; and S4, one year after MI) the following parameters were assessed: WMSI, EDVI, ESVI, LVEF, LV sphericity index (WSF), index of infarct expansion (EXP), restrictive pattern of mitral flow (RP), grade of mitral regurgitation (MR). The criterion of significant LV dilatation was EDVI ≥85 ml/m² and/or DEDVI ≥20% between two succeeding ECHO. At S3 pts were classified into groups: group 1 with no LV dilatation (n=68), group 2 with early transient LV dilatation (S1 and/or S2) (n=26), group 3 with progressive (S1 – S2 – S3) LV dilatation (n=28). The prognostic value of the following parameters was assessed: anterior infarct location, Q-wave MI, Killip-Kimball class ł2, lack of noninvasive assessed reperfusion R(–), EXP(+), CK ≥3000 IU, WMSI_S2 ≥1.5, EDVI_S2 ≥80 ml/m², ESVI_S2 ≥40 ml/m², EF_S2 <45%, RP_S2 and baseline LV hypertrophy (S1). Results: Patients in group 3 had significantly larger IS (WMSI) than in group 1 (p <0.01) and group 2 (p <0.05). Infarct expansion was found only in group 3. One year after MI in group 3 compared to groups 1 and 2 adverse remodelling was observed: lower EFS4 (p <0.001), more spherical LV (WSFS4) (p <0.001), higher rate of MR_S4 ≥2 (p <0.001) and RP_S4 (p <0.001). Within each group LVEFS1-S4 was stable in one-year follow-up. In group 3 incidence of heart failure (HF) was significantly higher than in groups 1 and 2 (respectively 57 vs. 2 vs. 4%; p <0.001). Cardiac death (CD) was observed only in group 3 (25% of pts). Increased EDVI ≥80 ml/m² at discharge was the most powerful independent predictor of progressive LV dilatation. Large IS (CK ≥3000 IU and/or WMSI ≥1.5) was not an independent predictor of adverse remodelling. Conclusions: 1) During the first 6 months after MI the progression of LV dilatation was a useful sign identifying adverse remodelling, even in the absence of LVEF evolutionary changes. Progressive LV dilatation was associated with more spherical LV and higher rate of MR ≥2°. 2) Patients with progressive LV were at higher risks of HF and CD in one-year follow-up. 3) Increased EDVI ≥80 ml/m² at discharge was the most powerful independent predictor of adverse postinfarction remodelling. Large IS was not an independent predictor. 4) Echocardiographic monitoring after MI is of great clinical importance – it enables pts at higher risk of HF and CD to be identified.