Echocardiographic and signal averaged ECG indices associated with non-sustained ventricular tachycardia after repair of tetralogy of Fallot

Objective-To identify any possible association between different readily av ailable non-invasive indices and potential malignant ventricular arrhythmia s in patients with repaired tetralogy of Fallot. Design-27 consecutive patients, mean (SD) age 27.3 (11.7) years, were studi ed 15.7 (6.7) years after corrective surgery for tetralogy of Fallot, using 12 lead EGG, 24 hour Holter recordings, signal averaged EGG, and echocardi ography. The following variables were measured: standard QRS duration, filt ered QRS duration (fltQRS), low amplitude signal duration, and root mean sq uare voltage of the last 40 ms of the fltQRS (RMS-40), as well as right ven tricular systolic pressure, right ventricular ejection fraction, and the ra tio of the maximum short axis diameters of the right and left ventricles (R D:LD). Results-All patients had right bundle branch block, with a mean QRS duratio n of 137.1 (14.9) ms. There were no patients with sustained arrhythmia. Fiv e patients had runs of non-sustained ventricular tachycardia (group A) and the other 22 patients did not (group B). Univariate analysis showed that fl tQRS and RD:LD ratio were significantly associated with nonsustained ventri cular tachycardia. In addition, a fltQRS greater than or equal to 148 ms, l ow amplitude signal greater than or equal to 32.5 ms, RMS-40 less than or e qual to 23 muV, and RD:LD ratio greater than or equal to 1.05 were cut off points with a high sensitivity for detecting patients with non-sustained ve ntricular tachycardia. Conclusions-Abnormal signal averaged ECG and echocardiographic variables ar e associated with potentially malignant ventricular arrhythmias on the Holt er recordings in asymptomatic patients with repaired tetralogy of Fallot.