Electrocardiographic differentiation of common type atrioventricular nodal reentrant tachycardia from atrioventricular reciprocating tachycardia via a concealed accessory pathway

Objective - The present study aimed to evaluate the diagnostic value of specific ECG markers in the differentiation of common type atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reentrant tachycardia (AVRT) via a concealed accessory pathway. Methods - One hundred and ten ECGs with paroxysmal narrow QRS complex, short RP tachycardia were evaluated. Subjects with overt ventricular pre-excitation during sinus rhythm were excluded from the study. The mechanism of arrhythmia was established during the electrophysiological study and confirmed by the efficacy of radiofrequency ablation. Results - Of the 110 patients, 74 displayed common type AVNRT and 36 AVRT. Predictors of AVNRT were the presence of pseudo r'-waves in lead VI [sensitivity 39.19%; specificity 97.14%; positive predictive value (PPV) 96.67%; negative predictive value (NPV) 43.04%] and pseudo S-waves in inferior leads (sensitivity 28.38%; specificity 94.29%; PPV 91.30%; NPV 38.37%). In the setting of visible P-waves, an RP interval <= 90 ms favoured the diagnosis of AVNRT (sensitivity 57.14%; specificity 80.65%). Predictors of AVRT were QRS alternans (sensitivity 50%; specificity 89.19%; PPV 69.23%; NPV 78.57%) as well as ST-segment alterations during tachycardia. The overall sensitivity, specificity, PPV and NPV of ST-segment depression for discriminating AVRT from AVNRT were 97.22%, 58.11%, 53.03%, 97.73%, respectively. Similarly, the sensitivity, specificity, PPV and NPV of ST-segment elevation in lead aVR were 94.44%, 58.11%, 52.31%, and 95.56%, respectively. Multiple logistic regression analysis showed that ST-segment depression [(odds ratio (OR): 12.67, 95% confidence interval (Cl): 1.77-90.81, P = 0.011)] and QRS alternans (OR: 9.43, 95% Cl: 1.38-64.37, P = 0.022) displayed the highest predictive ability favouring the diagnosis of AVRT. Conclusions - Twelve-lead ECG parameters may help to differentiate the mechanism of supraventricular tachycardia prior to the ablation procedure.