[Methods of evaluating proposed treatments in the secondary prevention of myocardial infarction]

Attempts at quantitative evaluation by imaging methods of left ventricular dys-synergism consecutive to ischaemia meet with a number of problems. These include such methodological and technical factors as corrections for heart movements in the thorax during contractions, or for the heterogeneity of segmental dynamics in both space and time. In addition, several biological factors must be considered, such as the possible expansion of a necrotic wall, the presence of systolic dysfunction in the area adjacent to the infarct, the lack of proportion between the degree of dys-synergism and the reduction in coronary arterial flow, and the frequent delay in improvement of contractile function after blood flow has been restored in the ischaemic area. A knowledge of all these factors is important to quantify myocardial ischaemia by imaging methods, and especially to evaluate the size of an acute infarct and the beneficial effects of early therapeutic measures on that size.