Background: Atrial fibrillation (AF) after coronary bypass graft surgery may result in hypotension, heart failure symptoms, embolic complications, and prolongation in length of hospital stay (LOHS). The purpose of this study was to determine whether intravenous diltiazem is more effective than digoxin for ventricular rate control in AF after coronary artery bypass graft surgery. A secondary end point was to determine whether ventricular rate control with diltiazem reduces postoperative LOHS compared with digoxin.
Methods and results: Patients with AF and ventricular rate > 100 beats/min within 7 days after coronary artery bypass graft surgery were randomly assigned to receive intravenous therapy with diltiazem (n = 20) or digoxin (n = 20). Efficacy was measured with ambulatory electrocardiography (Holter monitoring). Safety was assessed by clinical monitoring and electrocardiographic recording. LOHS was measured from the day of surgery. Data were analyzed with the intention-to-treat principle in all randomly assigned patients. In addition, a separate intention-to-treat analysis was performed excluding patients who spontaneously converted to sinus rhythm. In the analysis of all randomly assigned patients, those who received diltiazem achieved ventricular rate control (> or = 20% decrease in pretreatment ventricular rate) in a mean of 10 +/- 20 (median 2) minutes compared with 352 +/- 312 (median 228) minutes for patients who received digoxin (p < 0.0001). At 2 hours, the proportion of patients who achieved rate control was significantly higher in patients treated with diltiazem (75% vs 35%, p = 0.03). Similarly, at 6 hours, the response rate associated with diltiazem was higher than that in the digoxin group (85% vs 45%, p = 0.02). However, response rates associated with diltiazem and digoxin at 12 and 24 hours were not significantly different. At 24 hours, conversion to sinus rhythm had occurred in 11 of 20 (55%) patients receiving diltiazem and 13 of 20 (65%) patients receiving digoxin (p = 0.75). Results of the analysis of only those patients who remained in AF were similar to those presented above. There was no difference between the diltiazem-treated and digoxin-treated groups in postoperative LOHS (8.6 +/- 2.2 vs 7.7 +/- 2.0 days, respectively, p = 0.43).
Conclusions: Ventricular rate control occurs more rapidly with intravenous diltiazem than digoxin in AF after coronary artery bypass graft surgery. However, 12- and 24-hour response rates and duration of postoperative hospital stay associated with the two drugs are similar.