Effect of amiodarone on sinus node function in patients with sick sinus syndrome.

The effect of amiodarone on sinus node function has been studied in 9 patients with symptomatic sick sinus node as documented by Holter-ECG. All patients had programmable dual-chamber pacemakers. Sinus node activity was assessed by intermittently inhibiting the pacemakers before and after four weeks of oral amiodarone treatment. Sinus node function was not altered by amiodarone in 5 patients but was severely depressed in 4 patients. Thus, it is concluded that amiodarone cannot be used safely in all patients with the tachybrady syndrome for the treatment of symptomatic tachyarrhythmias without concomitant pacing.