In this episode, I’ll discuss the use of an initial 6 mg vs 12 mg dose of adenosine for supraventricular tachycardia.
One of my least favorite recommendations to give “by the book” is what dose of adenosine to use to terminate supraventricular tachycardia. While 6 mg is the recommended starting dose, it seems like more often than not, it doesn’t work, and a dose escalation to 12 mg is required for conversion.
A group of authors published a prospective observational study in Academic Emergency Medicine to compare the efficacy and safety of an initial 12 mg versus 6 mg adenosine dose for sinus rhythm conversion in patients presenting with supraventricular tachycardia (SVT) in the emergency department (ED).
Data from 142 patients split 1:1 into a 6 mg or 12 mg initial adenosine dose group each with hemodynamically stable SVT confirmed by ECG were analyzed. The primary outcome was successful first-dose sinus rhythm conversion. Secondary outcomes included adenosine-related adverse effects and SVT recurrence during the ED stay.
Conversion of SVT on the first dose was significantly higher with 12 mg compared with 6 mg (83.1% vs. 52.1%). When the propensity score matching cohort was analyzed, this difference was maintained. The adjusted odds ratio for successful conversion was 4.12 for the 12 mg dose with a number needed to treat of 3.8. In addition, SVT recurrence was numerically lower in the 12 mg group (1.4% vs. 9.9%). There was no difference detected between the groups in terms of adverse effects.
The authors concluded:
An initial 12 mg adenosine dose was associated with higher first-dose sinus rhythm conversion than 6 mg, while adverse effects were similar between groups…These findings suggest that initiating treatment with a 12 mg adenosine dose may represent a potentially effective alternative approach for the acute management of SVT in the ED. However, given the observational design of the study, these results should be interpreted as an association rather than evidence of causality.
While the main study results aren’t surprising as they match what I’ve seen in my experience, the most interesting part of the results to me is the more than 6-fold lower rate of SVT recurrence in the 12 mg group. I hope that whatever future studies are done that they are powered adequately to assess the SVT recurrence rates and not just initial termination.
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