A non-cardioselective beta-adrenergic antagonist devoid of intrinsic sympathomimetic & membrane-stabilizing actions. But unlike other b-blockers, it prolongs action potential duration recorded in cardiac tissue, increases the refractory period & lengthens QT interval.
It has less neg. inotrope activity than other b-blockers as it tends to increase contractility by prolongation of action potentials - but may aggravate CCF in some pts.
It is an effective antiarrhythmic agent & antifibrillatory agent.
It can cause torsade de pointes & thus although relatively safe after AMI, would not be recommended routinely as a substitute for other b-blockers;