The importance of utilizing 24-h Holter monitoring as a non-invasive method of predicting the mechanism of supraventricular tachycardia.

Despite the emergence of advanced invasive technology in identifying the various types of arrhythmia mechanisms, 24-h ambulatory electrocardiogram monitoring as a non-invasive method remains an invaluable informative tool in delineating such mechanisms. Furthermore, one observational study has supported the utilization of 24-h Holter monitoring in exploring AV Node (AVN) characteristics sufficiently in correlation with invasive studies when limited to patients without Wolf Parkinson White syndrome showing a positive predictive value of 98% in their supraventricular tachycardia (SVT) assessment (Fukuda et al., 2005). We describe in this report suspected tachycardia initiation mechanism in three SVT cases based on 24-h Holter recordings. Premature atrial contraction with subsequent AVN fast pathway conduction block initiated the common type AVN re-entrant tachycardia (AVNRT). Dual AVN physiology was documented during the electrophysiological studies in all three cases and a definitive therapy was achieved by the AVN slow pathway modification.