Comparative investigations on the antiarrhythmic and electrophysiologic effects of class I-IV antiarrhythmic agents following acute coronary artery occlusion.

The effects of class I to IV antiarrhythmic drugs on ventricular arrhythmias, particularly ventricular fibrillation, in relation to epicardial conduction delay during acute myocardial ischaemia were investigated in 40 open-chest anaesthetized dogs. In these animals transient coronary artery occlusion lasting 20 minutes was performed. Sixteen dogs served as controls; four groups of 6 dogs each received lidocaine (2 mg kg-1 + 50 micrograms kg-1 over 20 minutes), metoprolol (2 mg kg-1 i.v.), d-sotalol (5 mg kg-1 i.v.) and verapamil (0.25 mg kg-1 i.v.), respectively 5 minutes prior to coronary occlusion. Epicardial conduction delay was assessed by means of an epicardial mapping electrode array consisting of 42 bipolar electrodes. In the control group conduction delay displayed a bimodal time course in the ischaemic area with a maximum of 38 +/- 10 ms 6 minutes after coronary occlusion followed by a partial improvement after 12 to 15 minutes. After pretreatment with lidocaine the peak conduction delay in the ischaemic area was significantly increased (43.2 +/- 12), whereas metropolol (21.5 +/- 1.9), d-sotalol (16.6 +/- 3.7) and verapamil (16.3 +/- 3.1) significantly reduced conduction delay. Correspondingly, ventricular arrhythmias and fibrillation were almost completely prevented by metoprolol, d-sotalol or verapamil, but increased by lidocaine.(ABSTRACT TRUNCATED AT 250 WORDS)