Canadian Journal of Cardiology



      The etiology and mechanism of supraventricular tachycardia (SVT) are well understood, however there is no consensus on the acute treatment and medications for prevention of recurrent SVT in infants, and a number of medication choices are available. There are almost no controlled trials and medication choices are not necessarily evidence-based. The objective of this study was to compare the effectiveness of reported medication strategies for SVT in infants.


      A registry of infants < 1 year of age admitted to hospital with reentrant SVT and no hemodynamically significant heart disease were prospectively followed for one year at 11 international tertiary care centers. Additionally, a systematic review of studies on infant SVT in MEDLINE and EMBASE from inception until January 2021 was conducted. Data on demographics, symptoms, acute and maintenance treatments, and outcomes were collected. A total of 2534 infants with SVT were included from the Registry (n=108, median age 9 days [0-324], 70.8% male) and literature (n=2426, median age 14 days; 62.3% male). Patients from both groups had similar characteristics (Table 1) and were most commonly diagnosed with atrioventricular reentrant tachycardia (AVRT) in the Registry (50%) vs unspecified reentrant SVT in the literature (84.3%). Propranolol was the most prevalent acute (61.4%) and maintenance treatment (53.8%) in the Registry while digoxin was used sparingly (4.0% and 3.8%) (Table 1). In contrast, propranolol or digoxin monotherapy were used frequently in the literature acutely (31% and 33.2%) and for maintenance (17.8% and 10.1%) (p < 0.001). Combination therapy was more common in the Registry (21.8%) than literature (8.2%) (p < 0.001). No differences between medications in terms of acute or prophylactic treatment effectiveness were observed in the Registry cohort. Recurrent SVT was higher in the Registry (25.0%) compared to the literature (13.4%) (risk ratio 1.86, 95% CI 1.31-2.65, p < 0.001). Random effects meta-analysis of relevant studies resulted in an estimated recurrence rate of 27% and adverse event rate of 9% (Figure 1). There were 22 (0.9%) deaths reported in the literature vs none in the Registry.


      Findings from this study reflect the largest cohort of infants with SVT analyzed to date. Digoxin monotherapy was used less commonly by contemporary pediatric EP doctors. There was no difference in treatment effectiveness between antiarrhythmics to support one medication over the others. The overall recurrence risks on antiarrhythmic medications in both groups were low.
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