The electrocardiographic effect of successful accessory pathway ablation in a patient with minimal preexcitation

In patients with an accessory pathway (AP), the degree of preexcitation depends upon the intra-atrial conduction time through the AP, atrioventricular node, and the His-Purkinje system, and on the localization of the AP. We presented a 20-year-old male patient whose electrocardiogram exhibited minimal preexcitation due to a left lateral AP. He had tachycardia as the presenting complaint. Electrocardiography (ECG) showed a shortened PR interval, a pattern of right bundle branch block in V1, and a negative delta-wave activity in aVL. On electrophysiologic study, an AP was detected in the left lateral wall and atrioventricular re-entrant tachycardia was induced. After successful radiofrequency ablation of the AP, no apparent change from the baseline ECG findings was observed. However, detailed analysis of the intracardiac and surface ECG showed that the ablation was successful and there was a minimal change in the QRS morphology in aVL derivation.