Slow-infusion of calcium channel blockers in the emergency management of supraventricular tachycardia

Objective: To compare the efficacy of verapamil and diltiazem as slow infusions in terminating spontaneous supraventricular tachycardia (SVT) in the emergency department (ED). Method: Patients of at least 10 years of age who presented to our ED with regular narrow complex tachycardia not converted with a vagal manoeuvre with an ECG diagnosis of SVT were included. Those who were haemodynamically unstable were excluded. Patients were randomized to undergo either verapamil infusion at a rate of 1 mg/min to a maximum of 20 mg or diltiazem infusion at a rate of 2.5 mg/min to a maximum of 50 mg. Results: Eighty-one patients were randomized to receive verapamil infusion and 80 were randomized to receive the diltiazem infusion. There is no difference in success rate between verapamil (98.8%) and diltiazem (96.3%) infusion. The dose of medication required to convert 25, 50 and 75% of SVTs were 4.0, 5.0 and 8.0 mg for the verapamil infusion and 10.0, 12.5 and 17.5 mg for the diltiazem infusion. There was one complication in each group. Conclusion: Calcium channel blockers infusions were safe and efficacious in terminating spontaneous SVT. There was no difference between the success rates of verapamil and diltiazem infusions.