Effect of Sotalol on Heart Rate Variability m by Hotter Monitoring in Patients with Ventricular Arrhythmias Stefan H. Hohnloser, MD, Thomas Klingenheben, MD, Markus Zabel, MD, and Hanjijrg Just, MD Reducedvaf@lacUvttyhasbeendemonstratedto bsassodatedwlthanhweased rlskofsudden death. Asses&g the heart rate varlablllty as a measureoftbsautonomkcontroloftheheart hasbeenestabllshedasausefultoolfortherlsk -ofpatklMaf&WmyoCanlialInfarc- Mon. In the current study, heart rate varlabillty assewed by thns- and fwquenq-donunln mea- !SIl~WasdetermlnedfromHdterWlXMdln&sblB- fofeanddurlngtreatment wlthsotalolIn28pa- tlsntswithchronkventrku lararrhythmlas.lhs heartratevarlabHyatbasellm,waslndepen- dentofthepresence orabsenceofspontansous awhythmlasandofleftventricularfunction.Ther- apywlth sotalol produced a slgnlfkant lmprove- mentovercontrolvalueslnl~ofparasym- pathetktone(rootmeansquareofthedMerence In swxesslve RR Intervals, propoftkn ofadja- CelltRRllltelVakdHMellt by >I% msec, h@h- frequency pamw spectrum)= THIS lmpnmrment was not related to drug4nducsd changes In the meanheartrateortbssuppregsknofventrkular ectopk actlvt&y. These effects on heart rate varl- aMmymwm slgnlficantly to the overall emcacyproflleofsotalol. (AmJCardiol1993;72:67A-7lA) From the Department of Cardiology, University Hospital, Freiburg, Germany. Address for reprints: Stefan H. Hohnloser, MD, Department of Cardiology, University Hospital, Freiburg, Hugstetterstrasse 55, 7800 Freiburg, Germany. N eural activity has long been known to play a decisive role in the genesis of lethal ventricular arrhythmias.’ In recent years, experimentaP3 and clinica14,5 studies have demon- strated that reduced vagal activity is associated with an increased risk of sudden cardiac death. Assessingheart rate variability as a measure of the autonomic control of the heart has been estab- lished as a useful tool for further stratifying pa- tients after myocardial infarction with regard to their risk of dying suddenly.e Many of these patients demonstrate a high density of spontane- ous ventricular arrhythmias, and often are treated with antiarrhythmic drugs. The Cardiac Arrhyth- mia SuppressionTrial (CAST), however, has shown that certain antiarrhythmic agents actually in- crease the risk of sudden death.7 The reasons for this unexpected finding are not completely under- stood.8Currently, there is a paucity of data regard- ing the influence of antiarrhythmic drugs on the autonomic nervous system as assessed by means of heart rate variability, despite the fact that this method could provide important insights into the mechanismsof action of antiarrhythmic drugs. One study has examined the effects of flecainide, propafenone, and amiodarone on heart rate vari- ability, with the results showing a significant reduc- tion of the vagal tone during treatment with the 2 class Ic drugs.9Sotalol is a l3 blocker with class III antiarrhythmic activity. lo Since p blockers have been shown to increase the heart rate variability in healthy volunteers, l1 the current study was aimed at assessing the effects of sotalol on the heart rate variability in patients with chronic ventricular arrhythmias. METHODS Patient ellglblllty and excltion: Patients aged 2 18 years with symptomatic ventricular arrhyth- mias were recruited for the study. At baseline Holter monitoring, ventricular premature com- plexes averaging > 30/hour and repetitive ventric- A SYMPOSIUM: ANTIARRHYTHMIC DRUG THERAPY 67A