Early remodelling of the left ventricle in patients with myocardial infarction

Sequential alterations of left ventricular volumes and haemodynamics were studied in 29 patients between 4 days and 4 weeks after myocardial infarction. Left ventricular volume was determined by single photon emission computerized tomography (SPECT), infarct size by creatine kinase (CK) analysis, angiography and thallium201 SPECT. Left ventricular volume index (ml m-2) decreased in patients with small infarcts (74.5 +/- 4.9 vs 62.5 +/- 3.0, P less than 0.005), but increased significantly in patients with moderate (74.6 +/- 4.7 vs 83.6 +/- 5.0, P less than 0.0001) and large (71.7 +/- 4.8 vs 90.2 +/- 6.5, P less than 0.0001) infarctions between 4 days and 4 weeks after acute myocardial infarction. The latter groups contained almost two-thirds of our patients. This dilation occurred without significant changes in filling pressures (Swan-Ganz catheter) and resulted in significant augmentation and finally, normalization of stroke volume at 4 weeks (33.2 +/- 3.3 vs 42.6 +/- 2.9), despite persistently depressed ejection fraction (conventional radionuclide ventriculography). It is concluded that left ventricular dilatation post-myocardial infarction is structural (unchanged filling pressure) and compensatory (increased stroke volume) during the interval observed in this study.