Of 1,247 consecutive patients who underwent cardiac surgery, 297 (24%) developed a post-operative atrial
tachyarrhythmia. Of these patients, 201 were suitable for treatment according to the study protocol. All patients were initially given
digoxin 0.75 mg intravenously (i.v.). After two hours, those 156 patients whose atrial arrhythmias persisted were given a 2 mg/kg loading dose of
disopyramide (i.v.), followed by a constant i.v. infusion (0.4 mg kg-1 h-1) or oral
therapy (600 mg daily). Within a further 12 hours, 75 patients (48%) reverted to sinus rhythm, 24 within one hour. Thus 120/201 patients (60%) reverted to sinus rhythm within 14 hours of commencing
therapy. Reversion rates of those patients with both
atrial fibrillation and flutter (AF/AFL) were significantly lower than those with AF (p less than 0.001) or AFL (p less than 0.02) alone. A further 70 patients reverted to sinus rhythm in one to 13 (mean four) days on continued
drug therapy. Elective
cardioversion restored sinus rhythm in six subjects. Atrial arrhythmias persisted in five patients (2.5%) at hospital discharge. Side-effects of
disopyramide were noted in 19% of patients.
Urinary retention was common (11.5%). Four patients with
atrial flutter developed 1:1 atrioventricular conduction with the
disopyramide loading dose. One patient with
atrial fibrillation developed
ventricular tachycardia during injection of the loading dose of
disopyramide, but was successfully cardioverted to sinus rhythm. Two further patients developed significant
hypotension (less than 90 mmHg systolic).
Disopyramide is effective in the treatment of post-operative atrial
tachyarrhythmias, but its routine use in this situation may be associated with an unacceptably high incidence of side-effects.