Programmed electrical stimulation was performed in 12 patients with moderate to severe
congestive heart failure and
ventricular tachycardia (VT) to study possible arrhythmogenic properties of
ibopamine, a new orally active
dopamine agonist.
Ibopamine induced no significant changes in spontaneous cycle length, PR, QRS, QTc, AH or HV intervals, and also right ventricular effective refractory periods were unaffected (for paced cycle lengths of 600 and 430 ms, respectively, using 1 extrastimulus: 287 +/- 16 ms at baseline vs 283 +/- 27 ms after
ibopamine and 270 +/- 23 ms during the control study vs 262 +/- 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
ibopamine. 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 +/- 0.2 vs 2.7 +/- 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 electrocardiogram was abnormal in 11 and showed late potentials in 5 patients, but no changes occurred after
ibopamine. During hemodynamic evaluation, increases in cardiac (32%) and stroke volume (34%) indexes were seen after administration of 100 mg of
ibopamine, accompanied by a decrease in vascular resistance and filling pressures. Plasma
norepinephrine decreased significantly after
ibopamine (p = 0.02) but plasma
epinephrine was unaffected.(ABSTRACT TRUNCATED AT 250 WORDS)