BETA-ADRENERGIC-BLOCKADE ACCELERATES CONVERSION OF POSTOPERATIVE SUPRAVENTRICULAR TACHYARRHYTHMIAS

Background: Postoperative supraventricular tachyarrhythmia is a common complication of surgery. Because chemical cardioversion is often inef fective, ventricular rate control remains a principal goal of therapy. The authors hypothesized that patients with supraventricular tachyarr hythmia after major noncardiac surgery who receive intravenous beta-ad renergic blockade for ventricular rate control would experience conver sion to sinus rhythm at a rate that differs from those receiving intra venous calcium channel blockade. Methods: The rate of conversion to si nus rhythm at 2 and 12 h after treatment was examined in 64 cases of p ostoperative supraventricular tachyarrhythmia. After adenosine adminis tration, patients who remained in supraventricular tachyarrhythmia wer e prospectively randomized to receive either intravenous diltiazem or intravenous esmolol for ventricular rate control (unblinded). Loading and infusion rates were adjusted to achieve equivalent degrees of vent ricular rate control Results: Patients were similar with regard to age and Apache Bl score. Most patients in both groups had atrial fibrilla tion (esmolol, 79%; diltiazem 81%), and none experienced stable conver sion with adenosine. Patients randomized to receive esmolol experience d a 59% rate of conversion to sinus rhythm within 2 h of treatment, co mpared with only 33% for patients randomized to receive diltiazem (int ention to treat, P = 0.049; odds ratio, 2.9; 95% confidence interval 1 .046 to 7.8). After 12 h of therapy, the number of patients converting to sinus rhythm increased in both groups (esmolol, 85%; diltiazem, 62 %), and the rates of conversion no longer differed significantly. Vent ricular rates when supraventricular tachyarrhythmia began and after 2 and 12 h of rate control therapy were similar in the two treatment gro ups. The in-hospital mortality rate and length of stay in the intensiv e care unit were not significantly influenced by treatment group. Conc lusions: Among adenosine-resistant patients in the intensive care unit with atrial fibrillation after noncardiac surgery, intravenous esmolo l produced a more rapid (2-h) conversion to sinus rhythm than did intr avenous diltiazem.