Initial adenosine dosing in SVT: A meta-analysis comparing 6 mg versus 12 mg across prehospital and emergency settings

Introduction: Supraventricular tachycardia (SVT) is a common arrhythmia that often requires urgent pharmacologic intervention. While current guidelines recommend a stepwise dosing strategy of intravenous adenosine (6 mg followed by 12 mg if needed), clinical practice increasingly favors using 12 mg as the initial dose. The optimal first-dose strategy remains uncertain. Material and methods: This is a systematic review and meta-analysis of research comparing the initial intravenous adenosine dose for adults with hemodynamically stable SVT between 6 and 12 mg. PubMed, Embase, Scopus, Web of Science, and CENTRAL were among the databases that were searched (through June 2025). Randomized trials and observational cohort studies that documented conversion to sinus rhythm following the initial dosage were among the studies that qualified. First-dose efficacy was the main outcome, with adverse events, repeat dosing, and hospital disposition as secondary outcomes. A random-effects model was used to compute pooled effect estimates, and ROBINS-I was used to evaluate the risk of bias. Results: Three retrospective cohort studies (total n = 11,686) satisfied the inclusion criteria. Pooled analysis indicated that a 12 mg first dose was substantially more efficacious than 6 mg in attaining conversion to sinus rhythm (OR 1.89, 95% CI 1.66–2.15, p < 0.00001; I² = 9%). The 12 mg cohort necessitated fewer repeat doses and had a reduced likelihood of hospital admissions (OR 0.72, 95% CI 0.59–0.87). No notable discrepancies in severe adverse events were detected across the groups. Conclusions: A 12 mg initial adenosine dose considerably enhances first-attempt cardioversion in adult SVT patients without raising the risk of side effects. These results imply that a one-step 12 mg strategy may be more effective than the conventional 6–12 mg stepwise approach, which calls for a reexamination of future guideline recommendations.