Carvedilol and vesnarinone: new antiarrhythmic approach in heart failure therapy.

Carvedilol and vesnarinone are drugs attracting recent interest in the treatment of chronic heart failure. Electrophysiologic studies have revealed that these drugs cause a moderate prolongation of action potential duration (APD) of ventricular muscles with minimal "reverse frequency-dependence" through different ionic mechanisms. Carvedilol blocks L-type Ca2+ current (ICa), transient outward K+ current (Ito), and delayed rectifier K+ current (IK) preferentially for the rapidly activating component (IKr). Vesnarinone is a selective blocker of IK with a unique drug-channel interaction. From the voltage- and time-dependence of IK inhibition, vesnarinone is considered to bind the IK (mainly IKr) channel during the activated state and unbind during the closed state. These electropharmacologic profiles provide a new approach for the development of an ideal antiarrhythmic drugs in patients with structural heart diseases.