Response heterogeneity in patients with vagal-refractory paroxysmal supraventricular tachycardia treated with...

Paroxysmal supraventricular tachycardia (PSVT) is a common regular tachyarrhythmias presenting to emergency departments (ED). Adenosine is the first-line pharmacologic agent for vagal-refractory PSVT, yet the variability in individual response remains poorly understood. Identifying patient-specific factors influencing adenosine efficacy may guide personalized treatment strategies.

This retrospective, single-center, observational study included adult patients diagnosed with PSVT by electrocardiography between January 2023 and May 2025. Demographic, clinical, electrocardiographic and laboratory parameters were pre-specified and included in a multivariable logistic regression model to identify independent predictors of adenosine success. Adenosine was administered in incremental boluses of 6, 12, and, if necessary, 18 mg, consistent with local emergency protocol. The primary outcome was successful conversion to sinus rhythm following adenosine administration. Logistic regression analysis was performed to identify independent predictors of adenosine success.

A total of 298 patients were analyzed; 72.5 % achieved successful conversion. In multivariable logistic regression, higher ionized calcium levels were associated with increased odds of adenosine success (OR = 1.41 per 0.1 mmol/L, 95 % CI 1.04-1.81). Additionally, a history of antiarrhythmic drug use (OR = 0.32, 95 % CI 0.15-0.68, p = 0.003) and the presence of heart failure (OR = 0.30, 95 % CI 0.10-0.88, p = 0.029) independently reduced the likelihood of successful conversion.

Adenosine response in PSVT is influenced by individual clinical and biochemical factors. Elevated ionized calcium enhances treatment success, whereas heart failure and antiarrhythmic medication history diminish efficacy. These findings highlight the importance of individualized adenosine dosing strategies in optimizing PSVT management in the emergency setting.