To compare the rate-lowering effect of diltiazem and two amiodarone regimens in critically ill patients with recent-onset atrial tachyarrhythmias.
Prospective, randomized, controlled study.
Medical cardiologic intensive care unit in a university hospital.
Sixty critically ill patients (Acute Physiology and Chronic Health Evaluation [APACHE] III score 70 ± 30, age 67 ± 10 yrs).
Patients with atrial fibrillation (n = 57), atrial flutter (n = 2), or atrial tachycardia (n = 1, and a heart rate consistently >120 beats/min over 30 mins were randomly assigned to one of three intravenous treatment regimens. Group 1 received diltiazem in a 25-mg bolus followed by a continuous infusion of 20 mg/hr for 24 hrs, group 2 received amiodarone in a 300-mg bolus, and group 3 received amiodarone in a 300-mg bolus followed by 45 mg/hr for 24 hrs.
The primary study end point was a >30% rate reduction within 4 hrs. The secondary study end point was a heart rate <120 beats/min (a patient was considered to have uncontrolled tachycardia if heart rate was >120 beats/min 4 hrs after study drug). The primary study end point was achieved in 14/20 (70%), 11/20 (55%), and 15/20 (75%) of patients in groups 1, 2, and 3, respectively (χ2 = 1.95, p = .38). Uncontrolled tachycardia was more frequently observed in group 2 (0/20, 9/29 [55%], and 1/20 [5%] of patients in groups 1, 2, and 3, respectively; χ2 = 17, p = .00016). In patients achieving tachycardia control, diltiazem showed a significantly better rate reduction (p = .0001 group 1 vs. group 3, p = .0001 over time;p = .0001 group 1 vs. group 2, p = .001 over time) when compared with the amiodarone groups. Premature drug discontinuation due to hypotension was required significantly more often in group 1 (6/20 [30%], 0/20, and 1/20 [5%] for groups 1, 2, and 3, respectively; χ2 = 10, p = .01).
Sufficient rate control can be achieved in critically ill patients with atrial tachyarrhythmias using either diltiazem or amiodarone. Although diltiazem allowed for significantly better 24-hr heart rate control, this effect was offset by a significantly higher incidence of hypotension requiring discontinuation of the drug. Amiodarone may be an alternative in patients with severe hemodynamic compromise.
From the Department of Cardiology, University of Vienna, Vienna, Austria.
Presented, in part, at the 28th International Educational and Scientific Symposium of the Society of Critical Care Medicine, San Francisco, CA, 1999.
Address for requests for reprints to: Georg Delle Karth, MD, Klinik für Innere Medizin II, Abteilung für Kardiologie, AKH WIEN, Waehringer Gürtel 18-20, 1090 Vienna, Austria. E-mail: georg.delle-karth@ univie.ac.at