Are infants with supraventricular tachycardia being over treated?

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A study published in Circulation: Arrhythmia and Electrophysiology indicates that infants (aged 0–1 year) with supraventricular tachycardia who receive medical prophylaxis do not have a first recurrence after six months of age-suggesting that the current approach of treating patients for the first year of life is too long.

Shubbhayan Sanatani (Children’s Heart Centre, British Columbia Children’s Hospital, Vancouver, Canada) and others commented that, at present, the management of supraventricular tachycardia in children has never been the subject of a randomised controlled trial. Therefore, the practice of using digoxin or propranolol as medical prophylaxis to prevent recurrence of supraventricular tachycardia is based on uncontrolled trial data. Sanatani et al added: “Based on uncontrolled, retrospective data, the recommendation has been to treat infants with supraventricular tachycardia for the first year of life even in the absence of recurrences.” They wrote that the purpose of their study was to “compare the efficacy and safety of the two most commonly used first-line therapies for supraventricular tachycardia prophylaxis in infants, digoxin and propranolol.”

Sanatani et al randomised patients (infants with supraventricular tachycardia aged 0–4 months) to digoxin or propranolol for six months or until one of the study’s endpoints was reached. The primary endpoint of the study was recurrence of supraventricular tachycardia after five days of study medication that required medical intervention to terminate (eg, administration of adenosine or other antiarrhythmics).

Of the 61 patients in the study, four patients on digoxin and seven patients on propranolol met the primary endpoint, which was a non-significant difference (12% vs. 18%; p=0.53). There was also not a significant difference in the rate of the primary endpoint between the two drugs in the intention-to-treat analysis (19% for digoxin vs. 31% for propranolol; p=0.25).

Furthermore, of the 51 patients who attended the 12-month follow-up visit, eight continued to have supraventricular tachycardia (four on digoxin and four on propranolol) and two continued to receive medication despite having no recent episodes of supraventricular tachycardia. Sanatani et al reported: “All 10 of these patients experienced their first documented recurrence of supraventricular tachycardia before six months of age. No patient had a documented first recurrence of supraventricular tachycardia in the six to 12-month follow-up.”

According to Sanatani et al, their study supports the current practice of digoxin or propranolol being acceptable first-line agents for the management of supraventricular tachycardia in infants. However, they added that the natural history of supraventricular tachycardia is probably “more benign” than previously thought as recurrences were uncommon in both treatment groups. Also, as recurrences occurred within the first four months of life for the majority of patients, the current practice of providing medical prophylaxis for a year may be too long. Sanatani et al noted: “This finding suggests that the duration of prophylactic medication may be shortened, although ongoing vigilance for recurrences is warranted and placebo-controlled data are needed to define the optimal time for medication withdrawal.”

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