WHY THE TRIAL IS NEEDED NOW Management of infant SVT is confounded by several factors, including the variable clinical course, the inability to predict recurrence, and the 'unknown' natural history in terms of resolution of arrhythmia substrate. This creates a challenge for health care practitioners and families. Our preliminary survey demonstrated a discrepancy between pediatric electrophysiologists and pediatric cardiologists in their medication choice for treatment of infant SVT [12]. It is not clear why the 'experts' (the electrophysiologists) manage SVT differently than do the majority of physicians who see infants with SVT. Most importantly, these treatment decisions are being made without clear evidence to support these choices. The differences in medication choice may reflect concern over case reports of rapid conduction and atrial arrhythmias with digoxin use in the setting of Wolff-Parkinson-White syndrome [2, 9, 27, 40]. It may be that electrophysiologists do not choose digoxin because of reports of high recurrence rates [10, 20, 26]; it is not clear whether digoxin poses a risk in the first year of life [17, 41]. Propranolol is reported to be effective at preventing recurrences and continues to be recommended for use [2, 6, 16]. Furthermore, interpretation of the existing body of knowledge poses several limitations. For example, almost all studies of SVT in childhood are retrospective in nature, spanning many years, and include studies of patients with varying forms of SVT, including those with Wolff-Parkinson-White syndrome and those with structural heart disease. In many cases, treatment failures and successes are not defined consistently, and multiple medication regimens are common. At the conclusion of these studies, reference is frequently made to the need for a controlled clinical trial. The lack of controlled trial outcomes, in turn, is cited as a key limitation for interpreting existing published data [8, 26].