Clonidine for patients with rapid atrial fibrillation

To determine whether clonidine can slow ventricular rate in patients with rapid atrial fibrillation.

Randomized, controlled trial, with a 4-hour follow-up period.

Emergency room of a university hospital.

A consecutive sample of 18 hemodynamically stable patients who were evaluated or treated for rapid atrial fibrillation. Exclusion criteria included acute or terminal illness; current use of antiarrhythmic agents, calcium-channel blockers, or beta-blockers; excessive hypertension; pulmonary, valvular, or pericardial disease; and electrolyte imbalance.

Patients were randomly assigned to receive either "no treatment" (control group) or clonidine, 0.075 mg orally, at baseline and after 2 hours if heart rate did not decrease by at least 20%.

Blood pressure was measured by the same nurse in the same arm for 4 consecutive hours, and a full 12-lead electrocardiographic evaluation was done.

Heart rate decreased to below 100 beats/min in eight of nine patients receiving clonidine compared with two of nine patients in the control group. The difference in the mean decreases in heart rate was 38 beats/min (95% CI, 20 to 56 beats/min). Six patients who were treated with clonidine and one patient in the control group reverted to normal sinus rhythm. Systolic blood pressure decreased slightly in both groups, without significant differences. Clinical follow-up was uneventful.

Low-dose clonidine was an easy, efficient, and effective treatment for patients with rapid atrial fibrillation who were hemodynamically stable.