BackgroundCryoballoon (CB) ablation of pulmonary vein ostia often induces a vagal response. This prospective study was designed to assess the effectiveness of prophylactic intravenous administration of atropine on hemodynamic impairment induced by CB ablation in patients with atrial fibrillation. MethodsTwenty-five patients with paroxysmal atrial fibrillation undergoing CB ablation were prospectively enrolled and assigned to one of two groups. First 12 patients (trial group) were administered 1 mg of atropine before deflation of the CB, while the following 13 patients (control group) were given atropine only after the onset of the hemodynamic variation (decrease in heart rate and/or blood pressure). Treatment was considered effective when the hemodynamic variations were restored. ResultsIn the trial group, three patients with transient hypotension did not require supportive care throughout the procedures, and one patient with hypotension required supportive care. In the control group, hypotension, bradycardia, and mixed bradycardia with hypotension requiring supportive care occurred in six, three, and three patients, respectively. Overall, the rate of marked vagal responses was significantly lower when prophylactic atropine was administrated (4/12 patients vs 12/13 patients, respectively; P < 0.01). ConclusionsAtropine is significantly effective in the prevention of all types of vasovagal responses induced by CB ablation in patients with atrial fibrillation.