Precordial electrocardiographic mapping. A technique to assess the efficacy of interventions designed to limit infarct size.

THE QUANTITY OF MYOCARDIUM which becomes necrotic following coronary occlusion has been shown to influence both the acute and long-term conse- quences of myocardial infarction.1 2 Fortunately, ex- periments now indicate that the size of a myocardial infarct is not irrevocably determined immediately following a cor- onary occlusion, but can be altered substantially by a number of interventions.3-1-However, the clinical assess- ment of interventions designed to protect ischemic myocar- dium has posed considerable difficulty. Precordial electro- cardiographic mapping, including analysis of both the ST segment and the QRS complex, which has been developed over the past several years, is now being used in studies on patients with acute myocardial infarction. In this review evidence will be presented which indicates that electrocar- diographic mapping, when employed properly and with ap- propriate awareness of its limitations, can yield valid results and indicate whether or not an intervention modifies either the severity of ischemia itself or the eventual size of an in- farction.