Background: The 2020 ACLS algorithm for treatment of SVT recommends an initial adenosine dose of 6 mg, followed by 12 mg via rapid IV push if cardioversion is unsuccessful. Among more recent studies evaluating adenosine dosing, between 45% and 70% of patients required escalation to 12 mg to achieve successful cardioversion, suggesting that the standard 6 mg dose may not be effective for some patients. However, evidence evaluating the use of a 12 mg initial dose is limited.  

Study design: Sert et al. conducted a prospective, single-center, observational study of 142 adult patients with SVT in a tertiary care emergency department in Turkey between February 2025 and January 2026. Patients received an initial dose of either 6 mg or 12 mg of adenosine (n=71 per group), selected at the discretion of the treating physician. Adenosine was administered using a proximal IV line using a T-connector or stopcock over 1-2 seconds. Patients with clinical signs of instability were excluded. 

Results: More patients in the 12 mg group experienced first-dose conversion compared to the 6 mg group (83.1% vs. 52.1%, p <0.001). Results were consistent among a 1:1 propensity-matched cohort (n=104) adjusted for age, sex, and history of SVT (82.7% vs. 53.8%, p <0.001). Similar rates of adverse events such as chest tightness, flushing, and shortness of breath were observed between the two dosing groups.  

Study limitations: Non-randomized design leaves potential for selection bias, results not adjusted for confounding factors such as quantified caffeine intake or absolute body weight, limited generalizability in settings where alternative methods of adenosine administration are used (i.e. single-syringe method), low sample size

Bottom line: This study adds to the growing body of evidence suggesting that an initial 12 mg dose of adenosine may be a safe and more effective alternative to the standard 6 mg dose.

References

Sert ET, Kokulu K, Yürük O, Akar EH, Topuz MA. Initial 12 mg versus 6 mg adenosine for supraventricular tachycardia in the emergency department. Acad Emerg Med. 2026; 33:e70309. PMID: 42057249