PRELIMINARY ANIMAL AND CLINICAL-EXPERIENCES USING AN ELECTROMECHANICAL ENDOCARDIAL MAPPING PROCEDURE TO DISTINGUISH INFARCTED FROM HEALTHY MYOCARDIUM

Background-A catheter-based left ventricular (LV) endocardial mapping procedure using electromagnetic field energy for positioning of the ca theter tip was designed to acquire simultaneous measurements of endoca rdial voltage potentials and myocardial contractility. We investigated such a mapping system to distinguish between infarcted and normal myo cardium in an animal infarction model and in patients with coronary ar tery disease. Methods and Results-Measurements of LV endocardial unipo lar (UP) and bipolar (BP) voltages and local endocardial shortening we re derived from dogs at baseline (n=12), at 24 hours (n=6), and at 3 w eeks (n=6) after occlusion of the left anterior descending coronary ar tery. Also, 12 patients with prior myocardial infarction (MI) and 12 c ontrol patients underwent the LV endocardial mapping study for assessm ent of electromechanical function in infarcted versus healthy myocardi al regions. Tn the canine model, a significant decrease in voltage pot entials was noted in the MI zone at 24 hours (UP, 42.8+/-9.6 to 29.1+/ -12.2 mV, P=0.007; BP, 11.6+/-2.3 to 4.9+/-1.2 mV, P<0.0001) and at 3 weeks (UP, 41.0+/-8.9 to 13.9+/-3.9 mV, P<0.0001; BP, 11.2+/-2.8 to 2. 4+/-0.4 mV, P<0.0001), No change in voltage was noted in zones remote from MI. In patients with prior MI, the average voltage was 7.2+/-2.7 mV (UP)/1.4+/-0.7 mV (BP) in MI regions, 17.8+/-4.6 mV (UP)/4.5+/-1.1 mV (BP) in healthy zones remote from MI, and 19.7+/-4.3 mV (UP)/5.8+/- 1.0 mV (BP) in control patients without prior MI (P<0.001 for MI value s versus remote zones or control patients). In the canine model and pa tients, local endocardial shortening was significantly impaired in MI zones compared with controls. Conclusions-These preliminary data sugge st that infarcted myocardium could be accurately diagnosed and disting uished from healthy myocardium by a reduction in both electrical volta ge and mechanical activity. Such a diagnostic electromechanical mappin g study might be clinically useful for accurate assessment of myocardi al function and viability.