A prognostic index for the successful use of adenosine in patients with paroxysmal supraventricular tachycardia in emergency settings: a retrospective study.

Study Objectives: The use of adenosine on failure of vagal maneuvers in patients with paroxysmal supraventricular tachycardia (PSVT) is recommended. The aim of the present study was to identify a possible prognostic index for the efficacy of adenosine in PSVT.

Methods: This retrospective study included 321 patients with PSVT, in whom vagal maneuvers failed to restore normal sinus rhythm and who received 6 mg adenosine, followed by 12 mg adenosine (repeated if necessary). A 2-step clustering algorithm was used to reveal nonapparent groupings. Various patients' characteristics were inserted into the model.

Results: A straightforward index has been chosen that would aid the distinction of patients failing to respond to adenosine. The formula, (age / heart rate at admission) + number of past PSVT episodes, was chosen as the one that combined the highest sensitivity (96.2%) and specificity (71.2%).

Conclusions: This prognostic index constitutes a useful and reliable bedside diagnostic tool to identify patients with PSVT who were less likely to respond to adenosine administration in the emergency setting.