INFLUENCE OF TRANSDERMAL SCOPOLAMINE ON CARDIAC SYMPATHOVAGAL INTERACTION AFTER ACUTE MYOCARDIAL-INFARCTION

In 41 survivors of acute myocardial infarction (AMI) a prospective stu dy was performed in 2 sequential phases. In phase 1, the role of baror eflex sensitivity and heart rate variability as predictors of inducibl e and spontaneous sustained ventricular tachyarrhythmias was evaluated . In phase 2, the effects of transdermal scopolamine on baroreflex sen sitivity, spectral and nonspectral measures of heart rate variability were investigated. At a mean follow-up of 10 +/- 3 months after AMI, 5 of 41 patients (12%) developed a late arrhythmic event. Of these, all (100%) had inducibility of sustained monomorphic ventricular tachycar dia at programmed stimulation compared with 3 of 36 patients (8%) with out events (p <0.0001). At multivariate analysis, baroreflex sensitivi ty had the strongest relation to both inducibility of sustained monomo rphic ventricular tachycardia (p <0.0001) and occurrence of arrhythmic events (p <0.0001). Of 41 patients, 28 (68%) consented to undergo pha se 2 of the investigation. Baroreflex sensitivity significantly (p <0. 00001) increased after transdermal scopolamine as well as heart rate v ariability indexes. Of these, the mean of SDs of normal RR intervals f or S-minute segments (p <0.0001) and the total power (p <0.0001) had t he most significant improvement after scopolamine. The present investi gation confirms that assessment of autonomic function is an essential part of arrhythmic risk evaluation after AMI. Transdermal scopolamine, administered to survivors of a recent AMI, reverses the autonomic ind exes that independently predict arrhythmic event occurrence. On the ba sis of these data, transdermal scopolamine could be a potential useful tool in the prophylaxis of life-threatening ventricular arrhythmias a fter AMI.