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A starting dose of 12mg of adenosine for stable supraventricular tachycardia (SVT) resulted in higher initial successful cardioversion rates and persistence of sinus rhythm thereafter without increased adverse effects.
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Written by Ketan Patel
Skip the warm-up: going straight to 12 mg for SVT in the ED
Despite higher initial success rates with a higher starting dose of adenosine, the adverse effects of that strategy along with efficacy of cardioversion and maintenance of sinus rhythm have not been clearly studied nor delineated.
This prospective observational study evaluates whether an initial 12 mg versus 6 mg IV adenosine dose improves first-dose sinus rhythm conversion in hemodynamically stable SVT. Among 142 ED patients (71 per group), first-dose success was 83.1% with 12 mg vs. 52.1% with 6 mg. In a propensity-matched cohort (n=104), success remained higher with 12 mg (82.7% vs 53.8%; OR 4.12 (95%CI 1.85–9.14); RR 1.42 (95%CI 1.15–1.74; NNT 4).
This study is a single-center, non-randomized design with physician-selected dosing, modest sample size, limited covariate adjustment in propensity matching, and short ED-only follow-up, which constrains causal inference and generalizability across different practice settings and SVT phenotypes.
How does this change my practice?
Selectively in practice, I have reached straight for 12mg, especially in patients who are apprehensive about the side effects (impending sense of doom). This study, however, isn’t sufficient to debunk the SVT strategy we all typically follow on the principles of ACLS, but it does open an opportunity for joint decision making with the right patient when the opportunity arises.
Source
Initial 12 mg Versus 6 mg Adenosine for Supraventricular Tachycardia in the Emergency Department. Acad Emerg Med. 2026 May;33(5):e70309. doi: 10.1111/acem.70309. PMID: 42057249; PMCID: PMC13128986.
