Areas of uncertainty remain, including interventions for which advanced technology is less important.
For example, vagal maneuvers are recommended in many circumstances as first-line intervention in patients
with SVT, but they are often ineffective. Furthermore, there is great variation in the way these maneuvers are
administered. Therefore, research on the best technique of vagal maneuvers, with dissemination of the findings,
is necessary. Clinical trials on antiarrhythmic drugs for SVT have been limited, and data are often extrapolated
from studies that primarily focused on management of patients with AF. The efficacy of a variety of drugs is
likely to differ according to the tachycardia mechanism, and therefore differentiating the best drug for each
individual arrhythmia is necessary; for example, the efficacy of class III agents might be markedly different in
patients with AF than in patients with atrial flutter. Limited data exist on the optimal management of less
common types of SVTs, such as junctional tachycardia and multifocal AT. Therefore, in view of significant
gaps that remain with regard to optimal management of patients with SVT, we must consider the role of
electronic medical records, registries, and national datasets to better acquire observational data when trials are
not available or feasible. Multicenter registry studies would allow for expansion of our knowledge on the best
pharmacological and nonpharmacological approaches to treat these arrhythmias. In collaboration with national
societies, the National Institutes of Health, and the U.S. Food and Drug Administration, registries could be
developed across selected centers to gather important information on safety and long-term outcomes where data
are lacking (just as such registries are being developed for AF ablation). Mandatory postmarket surveillance
data collection on new drugs for SVT could also be considered by the U.S. Food and Drug Administration as a
condition for drug approval.