The diagnosis of SVT is often made in the emergency department, but it is common to elicit symptoms suggestive of SVT before initial electrocardiogram/electrocardiographic (ECG) documentation. SVT symptom onset often begins in adulthood; in 1 study in adults, the mean age of symptom onset was 32 18 years of age for AVNRT, versus 23 14 years of age In contrast, in a study conducted in pediatric popu- lations, the mean ages of symptom onset of AVRT and AVNRT In comparison with AVRT, patients with AVNRT are more likely to be female, with an age AVNRT onset has been reported after the age of 50 years in 16% and before the age of 20 years in Among women with SVT and no other cardiovascular disease, the onset of symptoms occurred during childbearing years (eg, 15 to 50 years) in 58%.32 The first onset of SVT occurred in only 3.9% of women during pregnancy, but among women with an established history of SVT, 22% reported that pregnancy exacerbated their symptoms.58 SVT has an impact on quality of life, which varies according to the frequency of episodes, the duration of SVT, and whether symptoms occur not only with exercise but also at rest.53,59 retrospective study in which the records of patients <21 years of age with WPW pattern on the ECG were reviewed, 64% of patients had symptoms at presentation, and an additional 20% developed symptoms during follow-up.60 Modes of presentation included documented SVT in 38%, palpitations in 22%, chest pain in 5%, syncope in 4%, AF in 0.4%, and sudden cardiac death (SCD) in 0.2%.60 Although this was a pediatric population, it provided symptom data that are likely applicable to adults. 