Value and Limitations of Precordial ST-Segment Mapping

The importance of noninvasive techniques for following the evolution of ischemic injury in patients with acute myocardial infarction is indisputable. The current great interest in such methods stems from the realization that damage to more than 40% of left ventricular myocardium is incompatible with survival,¹and from extrapolation to the clinical situation of experimental data, which suggests that the initial ischemic injury may require some period of time for demarcation and cell death to occur.² One technique for following the progression of ischemic injury is the method of serial precordial mapping of the ECG. Clinical application of precordial mapping has followed several years of experimental work, during which epicardial electrograms were correlated with histological and histochemical evidence of necrosis resulting from coronary occlusion.³The observation that ST-segment elevations recorded simultaneously from the epicardium and precordium in dogs move in parallel during experimental manipulations that alter the magnitude