CRITERIA FOR LOCAL MYOCARDIAL ELECTRICAL ACTIVATION - EFFECTS OF ELECTROGRAM CHARACTERISTICS

Detection of local electrical myocardial activation by means of extrac ellular recordings is often difficult in the presence of polyphasic el ectrograms. The purpose of this investigation was to compare the abili ty of several variables to distinguish unipolar deflections due to loc al activation from those due to nonlocal activity. A model of polyphas ic deflections based on atrial recordings during reentrant tachycardia was used to facilitate distinction of local and distant activity by m ethods independent of the test variables. The performances of variable s were assessed by comparing areas under receiver operating characteri stic curves. Optimal thresholds of test variables were identified by m aximizing statistics which corrected for the pretest probability of lo cal activation. We found that the greatest negative first derivative o f the unipolar potential discriminated between local and distant ventr icular signals, but performed less well than the ratio of the first de rivative to the potential for distinguishing between local atrial sign als and distant ventricular signals. A linear combination of the poten tial and the ratio of the first derivative and the potential performed well for all groups of signals studied. We conclude that optimal crit eria for detecting local activation depends on the characteristics of the population of signals and that a statistical approach can be used to identify optimal criteria for a given population.