Bucindolol, a beta blocker, decreased ventricular fibrillation and maintained mechanical function in a pig model of acute myocardial ischemia

Bucindolol is a new beta blocker with marked vasodilatory properties and intrinsic sympathomimetic activity. We tested its potential effect against ventricular fibrillation (VF), in a pig model of acute myocardial ischemia. Bucindolol 6 mg/kg IV was administered in two equally divided doses, the first 30 minutes prior to, and the second 10 minutes after, ligation of the anterior descending coronary artery (CAL) in anesthetized open-chest pigs. Bucindolol decreased the incidence of VF to 1/11 versus 14/16 in the control group (p<0.005). Bucindolol also decreased the duration of ventricular tachycardia, 15±8 seconds versus 104±32 seconds in the control group (p<0.01). Bucindolol maintained LVmaxdP/dt at predrug and pre-CAL values, whereas LVmaxdP/dt was decreased by CAL in the control group. Bucindolol decreased arterial pressure and heart rate. Bucindolol increased blood flow in the peripheral ischemic zone (24.6±1.8% versus 16.2±1.7% (percent of pre-CAL value) in controls, p<0.002), as well as in the nonischemic zones (perlischemic zone: 126.4±6.1% versus 96.7±4.8% in the control group, p<0.0005; remote nonischemic zone: 126.6± 7.1% versus 87.1±4.3% of pre-CAL value in the control group, p<0.0001). Bucindolol had marked antiarrhythmic effects that were associated with beneficial effects on the mechanical function of the left ventricle and on blood flow to the ischemic myocardium.