[Cine-MRT in the functional and morphological diagnosis of the heart after a myocardial infarct/ A comparison with angiocardiography, 2-dimensional echocardiography, intracardiac scintigraphy and enzymatic infarct size estimation]

Changes of the left ventricle after myocardial infarction--estimation with cine magnetic resonance imaging during the first six months

BACKGROUND

In recent years, the interest of cardiologists has focused increasingly on the morphologic and functional changes of the left ventricle after myocardial infarction (MI), due to their great prognostic 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

In all, 61 patients (17 women, 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. According to enzyme-derived infarct weight, 15 patients had small infarcts (< 20 g), 19 had intermediate-sized infarcts (20-40 g), and 27 patients had large infarcts (> 40 g). CMRI was performed in the true short axis of the left ventricle. In each examination, left ventricular end-diastolic and end-systolic volume indices (LVEDVI, LVESVI), stroke volume index (LVSVI), ejection fraction (LVEF), and regional thickness, mass, and motility of the myocardial wall-diastolic thickness (IDdia), infarct mass (IM) and motility (IMOT) of the infarct area and diastolic and systolic thickness (VDdia, VDsys), muscular mass (VM), and motility (VMOT)-were determined. In addition, patients were divided into subgroups according to New York Heart Association (NYHA) functional status at baseline.

RESULTS

In the total group, LVEDVI increased from 73.9 +/- 23.5 ml/m2 to 85.4 +/- 28.1 ml/m2 (p < 0.001) and LVESVI from 40.5 +/- 19.4 ml/m2 to 51.2 +/- 29.0 ml/m2 (p < 0.001). In the subgroups the development depended on infarct size and location. LVSVI and LVEF remained more or less constant except for large anterior infarctions. All changes of the myocardial wall depended on infarct size and location: 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 total 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 subgroups changes varied: VDdia and VDsys decreased markedly in large anterior 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 pronounced in anterior infarctions. The volume-mass ratio, a measure of the success of compensation of volume increase by myocardial hypertrophy, decreased in small infarcts, remained unchanged in intermediate infarcts, and increased in large infarcts. There was a trend toward improvement of the NYHA functional status during the observation period.

CONCLUSIONS

Changes of the left ventricular chamber during the first 6 months following MI are dependent on its size and location, with large anterior infarctions having the worst course. Myocardial wall remodeling is also dependent on infarct size and location, and the volume-mass ratio increases in the presence of large areas of necrosis, indicating the non-compensatory effect of myocardial hypertrophy. However, these changes have no clinical effect during the first half year after MI.

Influence of tissue affinity of angiotensin-converting enzyme inhibitors on left ventricular remodeling after myocardial infarction

BACKGROUND

The demonstration of local renin-angiotension systems has raised the question of whether angiotensin-converting enzyme (ACE) inhibitors with different tissue affinities differ with regard to their effects on postinfarction remodeling.

HYPOTHESIS

The study was undertaken to investigate the influence of ACE inhibitors with different tissue affinity on morphology and function of the infarcted left ventricle.

METHODS

In all, 52 patients (17 women, 35 men, 38-73 years) with large acute myocardial infarction were randomized to receive either 25-75 mg/day captopril or 10-20 mg/day fosinopril beginning on the Day 7 after infarction. Of these, 28 had anterior and 24 had posterior wall infarctions. Infarct size was determined by the creatine kinase integral method. Fifty patients were examined by cinemagnetic resonance imaging (CMRI) 1 and 26 weeks after infarction. The following parameters were determined: left ventricular end-diastolic and end-systolic volume index (LVEDVI, LVESVI), ejection fraction (LVEF), infarct weight, and muscle mass (LVMM). The volume-to-mass ratio (VMR) was calculated and the clinical status according to the guidelines of the New York Heart Association (NYHA) was documented at each examination time. The results were compared with those of a historical sample without ACE-inhibitor therapy examined in an identical manner (n = 31, 10 women, 21 men, 36-75 years).

RESULTS

LVEDVI and LVESVI increased in the first 6 months after infarction by 24.9 and 36.6%, respectively, in the historical sample; by 11.0 and 7.8%, respectively, under captopril; and by 13.1 and 10.7%, respectively, under fosinopril. LVEF decreased by 14.9% in the untreated sample, by 3.7% under captopril and by 5.0% under fosinopril. Infarct weight and LVMM increased by 12.7 and 15.3%, respectively, without ACE inhibition, by 5.7 and 10.1%, respectively, in patients treated with captopril, and by 6.1 and 9.3%, respectively, in patients treated with fosinopril. The VMR increased by 7.4% in the historical sample, by 3.5% in the captopril group, and by 1.8% in the fosinopril group. The NYHA clinical status improved by 18.2% without ACE inhibition, by 42.9% in the captopril group, and by 26.3% in the fosinopril group. The differences between the two ACE-inhibitor groups and the reference group were all significant, while the differences between the captopril group and the fosinopril group were significant only for VMR (p < 0.01) and NYHA class (p < 0.05).

CONCLUSIONS

Both captopril and fosinopril have a comparable positive influence on postinfarction remodeling and on clinical status. Lipophilicity and tissue affinity do not seem to play a clinically important role in ACE-inhibitor therapy after infarction.