Protection against programmed electrical stimulation-induced ventricular tachycardia and sudden cardiac death by NE-10064, a class III antiarrhythmic drug.

The electrophysiologic and antifibrillatory properties of NE-10064 were studied in vivo in a conscious canine model of sudden cardiac death. Purpose bred male mongrel dogs weighing 14.5-21.5 kg were anesthetized, and surgical anterior myocardial infarction (MI) was induced by a 2-h occlusion, with reperfusion, of the left anterior descending coronary artery (LAD). Three to 5 days after induction of anterior wall MI, animals were subjected to testing by programmed electrical stimulation (PES). As compared with predrug incidence (12 of 12), NE-10064 (10 mg/kg intravenously, i.v.) reduced (p < 0.05) the incidence (8 of 12) of PES-induced ventricular tachycardia (VT). All but 1 control animal remained inducible after vehicle (5% dextrose in water). The cycle length of induced VT was not prolonged by NE-10064 (0.245 +/- 0.046 s predrug vs. 0.301 +/- 0.060 s postdrug). NE-10064 increased ventricular effective refractory period (VERP 166 +/- 5 ms predrug vs. 194 +/- 13 ms postdrug, p = 0.013), prolonged QTc interval (310 +/- 12 ms predrug vs. 350 +/- 16 ms postdrug, p = 0.004) and prolonged the effective refractory period (ERP) of noninfarcted myocardium (p = 0.045). The drug did not affect ECG-indexes of conduction velocity: QRS and P-R intervals were not affected, nor were activation delay and conduction time of noninfarcted and infarcted myocardium. In the sudden cardiac death protocol, NE-10064 protected (p = 0.018) against ischemia-induced ventricular fibrillation (VF, 75% survival with drug vs. 25% survival without drug). NE-10064 afforded protection (p = 0.040) throughout 14 h posterolateral ischemia in the presence of the previous anterior infarct.(ABSTRACT TRUNCATED AT 250 WORDS)