There was a lack of information on the likelihood of recurrence in newborns with supraventricular tachycardia (SVT). For a study, researchers set out to identify the prevalence and risk factors for SVT recurrence.

Infants with structurally normal hearts diagnosed with re-entrant SVT at age ≤1 year old were the subjects of this retrospective single-center study (1984–2020) with prospective phone follow-up. First, SVT recurrence upon hospital discharge was the primary outcome. A risk algorithm was developed using classification and regression tree analysis.

A total of 87% of the 460 newborns (62% males) had their illnesses identified at ≤60 days of age (median 13 days; IQR: 1-31 days). During a median follow-up of 5.2 years (IQR: 1.8-11.2 years), 33% had a recurrence. On multivariable analysis, factors associated with recurrence included: fetal or late (>60 days) diagnosis (HR: 1.90; 95% CI: 1.26-2.86; and HR: 1.73; 95% CI: 1.07-2.77, respectively), Wolff-Parkinson-White (WPW) syndrome (HR: 2.46; 95% CI: 1.75-3.45), and need for multi-antiarrhythmic or second-line therapy (HR: 2.08; 95% CI: 1.45-2.99). WPW was exposed to the greatest risk, according to the classification and regression tree analyses. Age at diagnosis was the most significant predictor of risk among individuals without WPW. Higher risk was associated with fetal or late diagnosis, and risk almost quadrupled if several antiarrhythmics or second-line treatments were also necessary. The risk of recurrence was lowest among infants without WPW who were detected quickly (0–60 days) and were discharged on propranolol.

Male infants with SVT are more likely to be diagnosed at or before 60 days of age. At the time of diagnosis, WPW, fetal or late diagnosis, and multi-antiarrhythmic or second-line treatment were risk factors for recurrence (occurred in 33%). Infants who got first-line monotherapy and were discharged with an early diagnosis, without WPW, have the lowest chance of recurrence.