Accuracy of electrocardiographic and echocardiographic indices in predicting life threatening ventricular arrhythmias in patients operated for tetralogy of Fallot

Objective-To validate the accuracy of the prognostic significance of non-in vasive clinical diagnostic indices as predictors of sustained ventricular t achycardia (sVT) or fibrillation (VF) in patients undergoing repair for tet ralogy of Fallot. Methods-One way analysis of variance and pairwise comparison of the values with the Bonferroni correction, logistic multivariate analysis, and ordinal logistic analysis were used to study quantitative electrocardiographic and echocardiographic variables in 66 patients who had undergone surgery for t etralogy of Fallot by ventriculotomy at a mean (SD) age of 11.8 (9.5) years . The mean (SD) period of follow up was 16.1 (5.7) years after surgery. Results-Four groups of patients were identified by ECG and 24 hour Holter m onitoring: 19 (28.7%) without ventricular arrhythmias, 34 (51.5%) with mino r ventricular arrhythmias, seven (10.6%) with non-sustained ventricular tac hycardia (nsVT), and six (9.0%) with sVT or VF. One way analysis indicated significant differences in QT dispersion (QTd) and end diastolic volume of the right ventricle (EDVRV) among the groups. Univariate logistic analysis showed EDVRV, QTd, and QRS duration to be significantly associated with sVT or VF. Stepwise multivariate analysis and ordinal logistic analysis showed QTd to be preferable to QRS duration as an indicator, because it was unrel ated to EDVRV, and was capable of separating different probability curves f or nsVT as opposed to sVT or VF. Conclusions-Stratification of patients undergoing corrective surgery for te tralogy of Fallot and at risk of life threatening arrhythmias is possible b y simple and inexpensive means, which provide sensitive and specific indice s.