Electrocardiographic predictors of right ventricular volume measured by magnetic resonance imaging late after total repair of tetralogy of Fallot

Background: Right ventricular dysfunction occurs in many patients with sign ificant pulmonary valve regurgitation late after initial total repair of te tralogy of Fallot. Methods to predict which of these patients are at increa sed risk of late morbidity and mortality are not yet known. Hypothesis: This study evaluated electrocardiographic (ECG) predictors of s evere right ventricular dilatation determined by magnetic resonance imaging (MRI) volumes in patients with tetralogy of Fallot late after initial corr ective repair. Methods: We retrospectively reviewed the ECGs and MRI right ventricular vol ume measurements of 20 patients (age 4.4 to 19.3 years, mean 10.0 years) wi th significant pulmonary valve regurgitation late after repair of tetralogy of Fallot. All patients had enlarged, hypokinetic right ventricles by echo cardiography. The patients were grouped based on an indexed right ventricul ar end-diastolic volume (RVEDV/BSA) of <102 ml/m(2) (Group 1) or greater th an or equal to 102 ml/m(2) (Group 2). We determined the sensitivity, specif icity, positive and negative predictive values of QRS duration, and mean fr ontal plane QRS axis for predicting right ventricular volumes. Results: A maximal QRS duration of greater than or equal to 150 ms northwes t quadrant frontal plane QRS axis had 85% sensitivity, 86% specificity, 92% positive predictive value, and 75% negative predictive value for predictin g an RVEDV/BSA of greater than or equal to 102 ml/m(2). The mean QRS durati on was significantly longer in Group 2 than in Group 1 patients (156 ms vs. 123 ms, p = 0.005). Conclusions: In patients late after repair of tetralogy of Fallot with sign ificant pulmonary valve regurgitation, a maximal manually measured QRS dura tion of greater than or equal to 150 ms and/or a frontal plane QRS northwes t quadrant axis can predict patients with marked right ventricular enlargem ent. The presence of either of these findings on the ECG signifies patients who require further evaluation and consideration for pulmonary valve repla cement.