Prehospital management of supraventricular tachycardia: a multicentre study of current practices with a subgroup propensity score-based comparison of adenosine and electrical cardioversion in unstable patients

Background: Supraventricular tachycardia (SVT) is a common prehospital arrhythmia that can cause life-threatening instability. Adenosine is the first-line treatment for stable SVT, but guidelines differ for unstable cases with hypotension, syncope, myocardial ischaemia, or severe heart failure. The European Resuscitation Council recommends electrical cardioversion (ECV), while the American Heart Association allows for an adenosine trial. This multicentre observational retrospective study evaluated global prehospital management strategies for SVT, subsequently focusing on adenosine vs ECV in unstable patients. Methods: Data from 2019 to 2024 were collected from three Italian physician-staffed Emergency Medical Services. Primary outcome was the rate of successful cardioversion; secondary outcomes included the presence of life-threatening complications following cardioversion. Finally, the diagnostic accuracy of available ECG traces was evaluated. Propensity score-weighted analysis was employed to control for potential cofounding variables. Results: Among 1234 SVT events, 819 (66.3 %) underwent prehospital cardioversion. Of these, 763 (93.2 %) received adenosine and 56 (6.8 %) underwent ECV. Unweighted cardioversion success rates were 80.1 % for adenosine and 83.9 % for ECV. In unstable patients, ECV had a weighted odds ratio of 2.41 (95 % CI: 1.01–7.14) for successful conversion. ECV was associated with more frequent sedative use compared to adenosine. No complications were observed in either groups. ECG diagnostic accuracy was 90.7 %, with dangerous misdiagnosis, such as ventricular tachycardia, occurring in fewer than 2 % of available ECG readings. Conclusions: In patients with prehospital SVT, adenosine is the preferred cardioversion strategy. In unstable cases, adenosine may be a safe first-line attempt before ECV, potentially reducing sedation-related risks. Trial registration: ClinicalTrials.gov Identifier: NCT06077799.