We assessed the electrophysiological properties of
prenalterol, a new beta-selective agonist, in 10 patients with normal and 10 patients with delayed atrioventricular (A-V) conduction times. We evaluated sinus node function, A-V conduction times, refractory periods, atrial or ventricular arrhythmias, spontaneous or induced by the single extrastimulus technique during basal conditions, 5 minutes after a first dose of 20 micrograms/kg of
prenalterol, and 5, 15 and 30 minutes after a second injection of the same dose.
Prenalterol increased heart rate about 20%, with statistically significant shortening of right atrial refractory periods, A-V nodal functional and effective refractory periods and A-H interval in both groups after the first dose. In the 6 patients with
sick sinus syndrome,
prenalterol increased heart rate significantly and decreased maximum sinus node recovery time which reached a statistically significant value (P less than 0.05) 5 and 30 minutes after the second dose. At the highest dose,
prenalterol seemed to increase the number of ventricular and/or atrial arrhythmias only in those patients with the arrhythmias before treatment.
Prenalterol increases heart rate and decreases A-V node conduction times. The shortening of maximum sinus node recovery time in patients with the
sick sinus syndrome, especially if confirmed after
oral administration, could indicate a specific use of this
drug in patients with sinus
bradycardia or
atrial fibrillation with a slow ventricular response.