A 12-year-old boy with Wolff-Parkinson-White syndrome presents with palpitations for the past hour. His blood pressure is 110/62 mm Hg and pulse is 166 bpm. The ECG reveals a narrow-complex tachycardia. Vagal maneuvers are ineffective. Which of the following is the next most appropriate management?
a) Adenosine
b) Cardioversion
c) Procainamide
d) Radiofrequency ablation