SIGNAL AVERAGING OF THE SURFACE QRS COMPLEX PREDICTS INDUCIBILITY OF VENTRICULAR-TACHYCARDIA IN PATIENTS WITH SYNCOPE OF UNKNOWN ORIGIN - A PROSPECTIVE-STUDY

[摘要] Forty patients with sncope of unknown origin underwent quantitative signal averaging of the surface QRS complex before invasive electrophysiologic testing with programmed ventricular stimulation. Of 34 patients without bundle branch block, 12 had inducible ventricular tachycardia (Group I) and 22 did not (Group II). The duration of low amplitude signals, the root mean square voltage of the terminal 40 ms and the signal-averaged QRS vector duration were measured in each case. One or more abnormal signal averaging variables were present in 92% of patients in Group I, but in only 27% of patients in Group II (p < 0.005), An abnormal root mean square voltage of the terminal 40 ms was the most significant distinguishing variable, being present in 83% of Group I patients and in only 14% of Group II patients (p < 0.005). The QRS vector duration was prolonged in 58% of Group I patients, but in only 9% of Group II patients (p < 0.05). Likewise, the duration of low amplitude signals was prolonged in 58% of Group I patients, but in only 19% of Group II patients (p < 0.05). When compared with 24 hour ambulatory electrocardiographic monitoring, the presence of abnormal signal averaging variables was more predictive of inducible ventricular tachycardia. Seven (32%) Group II patients had .gtoreq. 10 ventricular premature beats/h, couplets or episodes of nonsustained ventricular tachycardia; however none had abnormal late potentials recorded. In contrast, three patients (25%) in Group I had < 10 ventricular premature beats/h, although all in that group had one or more abnormal signal-averaged variables. The sensitivity and specificity of the various signal-averaged variables ranged from 50 to 83% and from 82 to 91%, respectively. An abnormally low root mean square voltage of the terminal 40 ms had the highest sensitivity (82%) and specificity (91%) in distinguishing individuals with syncope of unknown origin who had inducible ventricular tachycardia. Thus, signal averaging of the surface QRS complex is a useful noninvasive technique for selecting patients with syncope of unknown origin who should undergo programmed ventricular stimulation.

[发布日期] 1987-10-01