Electrophysiologic Profile of lbopamine in Patients with Congestive Heart Failure and Ventricular Tachycardia and Relation to Its Effects on Hemodynamics and Plasma Catecholamines Dirk J. Van Veldhuisen, MD, Harry J. Crijns, MD, Armand R. J. Girbes, MD, Tom J. M. Tob6, MD, Ans C. P. Wiesfeld, MD, and K. I. Lie, MD Programmed electrical stimulation was per- formed in 12 patients with moderate to severe congestive heart failure and ventricular tachy- cardia (VT) to study possible arrhythmogenic properties of ibopamine, a new orally active do- pamine agonist. lbopamine induced no signifi- cant changes in spontaneous cycle length, PR, QRS, QTc, AH or HV intervals, and also right ventricular effective refractory periods were un- affected (for paced cycle lengths of 600 and 430 ms, respectively, using 1 extrastimulus: 287 f 16 ms at baseline vs 263 f 27 ms after ibopa- mine and 270 f 23 ms during the control study vs 262 f 19 ms after ibopamine). In 6 of the 8 patients with coronary artery disease but in none of the 4 patients with dilated cardiomyopathy, sustained VT was induced before and after ibo- pamine. Proarrhythmia was present in 1 patient, who became inducible after ibopamine. However, 1 patient had sustained VT only at baseline but not after ibopamine. The number of extrastimuli required for VT induction was equal (2.7 f 0.2 vs 2.7 f 0.2). Holter monitoring showed no changes in ventricular premature complexes, ventricular couplets and runs of VT after 1 week of ibopamine therapy. The signal-averaged elec- trocardiogram was abnormal in 11 and showed late potentials in 5 patients, but no changes oc- curred after ibopamine. During hemodynamic evaluation, increases in cardiac (32%) and stroke volume (34%) kutexes were seen after administration of 100 mg of ibopamine, accom- panied by a decrease in vascular resistance and filling pressures. Plasma norepinephrine de- creased significantly after ibopamine (p = 0.02) but plasma epinephrine was unaffected. In con- clusion, ibopamine has no significant proarrhyth- mic effects in patients with congestive heart fail- ure and VT, presumably because of its favorable influence on hemodynamics and plasma norepi- nephrine levels. (Am1 Cardiol 1991;68:1194-1202) C ongestive heart failure (CHF) is a large epide- miologic and medical problem and is the only cardiac disorder that is still increasing in preva- lence.’ Although treatment with diuretics, digitalis and especially converting-enzyme inhibitors has been shown to reduce symptoms and prolong survival in CHF,2 many patients reach a stage where therapeutic control with these agents is not sufficient anymore. In this context, newer agents have been developed that act by increasing tissue cyclic adenosine monophosphate re- sulting in positive inotropic action and vasodilation. Al- though these oral inodilators, including phosphodiester- ase inhibitors, ,L3-adrenergic agonists and dopaminergic agents have shown beneficial short-term hemodynamic effects, their value in the long-term treatment of CHF may be offset by a propensity to cause proarrhyth- mia.3,4 I From the Departments of Cardiology/Thoraxcenter, Internal Medicine and Clinical Pharmacology, University Hospital Groningen, Groning- en, the Netherlands. This study was supported in part by a grant from Inpharzam Nederland BV, a division of Simes S.p.A.. Zambon Group, Milan, Italy. Manuscript received April 10, 1991; revised manuscript received and accepted June 26,199 1. Address for reprints: Dirk J. Van Veldhuisen, MD, Department of Cardiology/Thoraxcenter, University Hospital Groningen, Oostersin- gel 59,9713 EZ Groningen, the Netherlands. Ibopamine is a new orally active dopamine agonist that activates dopamine-, 0, and, at higher doses, (Yre- ceptors5 Earlier studies with ibopamine have shown beneficial hemodynamic effects.637 However, there are no data on its electrophysiologic or arrhythmogenic properties in patients with CHF. Because these studies are important to establish its clinical applicability, we performed programmed electrical stimulation before and after ibopamine administration in patients with CHF and ventricular tachycardia (VT). Furthermore, acute electrophysiologic changes were related to the in- 1194 THE AMERICAN JOURNAL OF CARDIOLOGY VOLUME 68 NOVEMBER 1, 1991