[Expansion and remodelling of the left ventricle after myocardial infarction]

The remodelling of the left ventricle after myocardial infarction results from the expansion of the infarcted zone in the acute phase and the dilation of the healthy zone of the left ventricle which complicates the initial expansion. It brings about an increase in the left ventricular volume which is a major pejorative prognosis factor after myocardial infarction. The expansion, defined by the dilation and parietal stricture of the infarcted zone, complicates about 30 p. cent of the infarctions and appears in the first hours of the infarction. It is favoured by the transmural nature of the infarction, by its extent and its previous topography, and by arterial hypertension. It is accompanied by a higher mortality rate, increases the risk of parietal rupture, exposes to post-infarction aneurysm and to intraventricular thrombi, and initializes the ventricular remodelling, factor of secondary cardiac failure. The dilation of the healthy zone of the left ventricle is observed mainly in case of initial expansion. Its importance increases with the size of the infarction. It corresponds to the volume overload secondary to the increase in the telediastolic parietal constraint of the left ventricle. The remodelling of the left ventricle after infarction is limited by captopril, and possibly by the restoration of the blood flow in the artery responsible for the infarction. Captopril, administered in the first weeks following the infarction, limits the dilation of the left ventricle in man as well as in animals. This beneficial effect is due to a decrease in the post-load of the left ventricle. Captopril improves the survival after infarction in animals, but its effect on the post-infarction mortality in man is still under study.