BACKGROUND: While clinical indicators for synchronized cardioversion in regular supraventricular tachycardias are well-established, their application by prehospital emergency medical services (EMS) still needs to be explored. OBJECTIVE: The purpose of this study was to evaluate the factors influencing the decision-making process of prehospital EMS personnel to perform synchronized cardioversion in adults with narrow QRS regular tachyarrhythmias. METHODS: This descriptive study included 598 paramedics actively engaged in prehospital EMS. Data were collected using a form that included questions about their experiences with synchronized cardioversion and presented three cases involving narrow QRS regular tachyarrhythmias. Since the data did not exhibit a normal distribution, the Mann-Whitney U test was employed to evaluate the significance of differences between the variables "number of previous SC applications" and "not performing SC despite recognizing unstable findings". RESULTS: The participants comprised 320 males (53.5 %) and 278 females (46.5 %). A majority (93.8 %, n = 561) had attended postgraduate training on synchronized cardioversion (SC) for adult patients, and 220 participants (36.8 %) reported prior experience performing synchronized cardioversion, with an average of three applications each. Despite recognizing sufficient clinical findings of unstable status for synchronized cardioversion in narrow QRS regular tachyarrhythmias, 177 participants (29.6 %) reported instances where they chose not to perform the procedure. Immediate synchronized cardioversion was preferred by 319 participants (53.3 %) in cases of altered mental status
however, this rate decreased to 16.9 % (n = 101) for ischemic chest discomfort and 30.4 % (n = 182) for acute heart failure cases. CONCLUSIONS: Previous experience with synchronized cardioversion and the proximity to the receiving hospital are key factors in the decision-making process. Additionally, the type of unstable finding is critical in making the decision for synchronized cardioversion.