SIGNIFICANCE OF ABNORMAL ROOT MEAN-SQUARE VOLTAGES IN SIGNAL-AVERAGEDELECTROCARDIOGRAM AS A RELIABLE PREDICTOR OF SUSTAINED VENTRICULAR-TACHYCARDIA

The late potential is useful to predict patients with sustained ventri cular tachycardia (VT). However, because positive predictive value for sustained VT is low, the validity of late potential for screening the patients to be studied by electrophysiological tests was not high. We examined 923 cases, including 63 cases of sustained VT. When we separ ated patients showing abnormal values of the root mean square voltage of the QRS end Dart 40 milliseconds (RMS40) into four groups, there wa s a tendency of a higher incidence of sustained VT with lower value of RMS40. When we conducted electrophysiological tests on 121 cases with out sustained VT, it turned out a high induction rate of sustained VT in patients with low RMS40 values (RMS40 < 10 mu V, 67%; < 20 mu V, 30 %; 20 mu V, less than or equal to 5%). We conclude abnormally low valu e (less than 10 mu V) of RMS40 can be useful for screening the late po tential-positive cases who are high risk for inducible sustained VT.