CHANGES OF THE LEFT-VENTRICLE AFTER MYOCARDIAL-INFARCTION - ESTIMATION WITH CINE MAGNETIC-RESONANCE-IMAGING DURING THE FIRST 6 MONTHS

Background: In recent years, the interest of cardiologists has focused increasingly on the morphologic and functional changes of the left ve ntricle after myocardial infarction (MI), due to their great prognosti c significance for the patient. Hypothesis: The aim of this study was to evaluate changes in left ventricular morphology and function during the first 6 months following MI. Methods: Ln all, 61 patients(17 wome n, 44 men, age 36-83 years) were examined with cine magnetic resonance imaging (CMRI) 1,4, and 26 weeks after myocardial infarction. Thirty- two patients had anterior MI and 29 patients had posterior MI. Accordi ng to enzyme-derived infarct weight, 15 patients had small infarcts (< 20 g), 19 had intermediate-sized infarcts (20-40 g), and 27 patients h ad large infarcts (>40 g). CMRI was performed in the true short axis o f the left ventricle. In each examination, left ventricular end-diasto lic and end-systolic volume indices (LVEDVI, LVESVI), stroke volume in dex (LVSVI), ejection fraction (LVEF), and regional thickness, mass, a nd motility of the myocardial wall - diastolic thickness (IDdia), infa rct mass (IM) and motility (IMOT) of the infarct area and diastolic an d systolic thickness (VDdia, VDsys), muscular mass (VM), and motility (VMOT) - were determined. In addition, patients were divided into subg roups according to New York Heart Association (NYHA) functional status at baseline. Results: In the total group, LVEDVI increased from 73.9 +/- 23.5 ml/m(2) to 85.4 +/- 28.1 ml/m(2) (p<0.001) and LVESVI from 40 .5 +/- 19.4 ml/m(2) to 51.2 +/- 29.0 ml/m(2) (p<0.001). Ln the subgrou ps the development depended on infarct size and location. LVSVI and LV EF remained more or less constant except for large anterior infarction s. All changes of the myocardial wall depended on infarct size and loc ation: In all patients IDdia decreased from 10.4 +/- 1.6 mm to 8.9 +/- 1.7 mm (p<0.001), IMOT from 2.0 +/- 1.6 mm to 0.5 +/- 2.9 mm (p<0.001 ). IM increased from 41 +/- 21 g to 45 +/- 25 g (p<0.001). In the tota l group, VDdia increased from 11.9 +/- 1.6 mm to 12.4 +/- 1.8 mm (p<0. 05), VDsys from 16.6 +/- 2.5 mm to 17.2 +/- 3.1 mm (p<0.05). In the su bgroups changes varied: VDdia and VDsys decreased markedly in large an terior wall infarctions. VM increased in the total cohort from a mean of 246 +/- 66 g to 276 +/- 80 g (p<0.001). VMOT decreased from 7.1 +/- 2.4 mm to 6.3 +/- 2.7 mm (p<0.05). Loss of motility was most pronounc ed in anterior infarctions. The volume-mass ratio, a measure of the su ccess of compensation of volume increase by myocardial hypertrophy, de creased in small infarcts, remained unchanged in intermediate infarcts , and increased in large infarcts. There was a trend toward improvemen t of the NYHA functional status during the observation period. Conclus ions: Changes of the left ventricular chamber during the first 6 month s following MI are dependent on its size and location, with large ante rior infarctions having the worst course. Myocardial wall remodeling i s also dependent on infarct size and location, and the volume-mass rat io increases in the presence of large areas of necrosis, indicating th e noncompensatory effect of myocardial hypertrophy. However these chan ges have no clinical effect during the first half year after MI.