Electromechanical mapping for detection of myocardial viability in patients with ischemic cardiomyopathy

Background-We evaluated the ability of electromechanical mapping of the lef t ventricle to distinguish between nonviable and viable myocardium in patie nts with ischemic cardiomyopathy. Methods and Results-Unipolar Voltage amplitudes and local endocardial short ening were measured in 31 patients (mean +/- SD age, 62 +/-8 years) with is chemic cardiomyopathy (ejection fraction, 30 +/-9%). Dysfunctional regions, identified by 3D echocardiography, were characterized as nonviable when PE T revealed matched reduction of perfusion and metabolism and as viable when perfusion was reduced or normal and metabolism was preserved. Mean unipola r voltage amplitudes and local shortening differed among normal, nonviable, and viable dysfunctional segments. Coefficient of variation for local shor tening exceeded differences between groups and did not allow distinction be tween normal and dysfunctional myocardium. Optimum nominal discriminatory u nipolar voltage amplitude between nonviable and viable dysfunctional myocar dium was 6.5 mV, but we observed a great overlap between groups. Individual cutoff levels calculated as a percentage of electrical activity in normal segments were more accurate in the detection of viable dysfunctional myocar dium than a general nominal cutoff level. The optimum normalized discrimina tory value was 68%. Sensitivity and specificity were 78% for the normalized discriminatory value compared with 69% for the nominal value (P<0.02). Conclusions-Endocardial ECG amplitudes in patients with ischemic cardiomyop athy display a wide scatter, complicating the establishment of exact nomina l values that allow distinction between viable and nonviable areas. Individ ual normalization of unipolar voltage amplitudes improves diagnostic accura cy. Electroanatomic mapping may enable identification of myocardial viabili ty.