Patterns of post-MI left ventricular volume changes - clinical implications.

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 > or =85 ml/m2 and/or DEDVI > or =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 > or =3000 IU, WMSIS2 > or =1.5, EDVIS2 > or=80 ml/m2, ESVIS2 > or =40 ml/m2, EFS2 <45%, RPS2 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 MRS4 > or =2 (p <0.001) and RPS4 (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 > or =80 ml/m2 at discharge was the most powerful independent predictor of progressive LV dilatation. Large IS (CK >/=3000 IU and/or WMSI > or =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 > or =2 degrees . 2) Patients with progressive LV were at higher risks of HF and CD in one-year follow-up. 3) Increased EDVI > or =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.