Can body surface mapping improve the diagnostic power of standard electrocardiography in effort myocardial ischemia?

Limitations of the standard 12-lead electrocardiogram in sensitivity, specificity and information content on the effort induced ischemic process might be partly due to an inadequate sampling of cardiac electrical events. An extensive array of electrodes is an effective way to verify this hypothesis. Actually body surface mapping provides: a 10-15% increase in diagnostic yield mainly in patients with mild coronary artery disease and elusive signs of ischemia in standard leads a very approximate indication of the extent of coronary artery disease a substantial contribution to the identification of the site of ischemia. Regarding the last point, preliminary results of an ongoing study are reported. One hundred and three patients with recent myocardial infarction have been studied by exercise test with simultaneous recording of surface map and Thallium 201 scan. So far in the subset with inferior myocardial infarction (76 patients) three different map patterns corresponding to different ischemic regions (anterior, inferior and posterior) have been identified. In anterior myocardial infarction (27 patients) a characteristic map pattern for exercise-induced myocardial ischemia has been observed, apparently able to discriminate between ischemia and the changes of early repolarization induced by the dyskinesia of the infarcted ventricular wall. In conclusion, electrocardiographic mapping makes a practical contribution to the understanding of ischemia-induced cardiac electrical events.