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Europace. 2004 Sep;6(5):384-91.

Evaluation of KCB-328, a new IKr blocking antiarrhythmic agent in pacing induced canine atrial fibrillation.

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Department of Pharmacology, College of Physicians and Surgeons of Columbia University, New York, NY 10032, USA.



KCB-328 is a new potassium channel blocker, which prolongs action potential duration with exhibition of minimal reverse use dependence. We tested the efficacy and proarrhythmic potential of KCB-328, dofetilide and propafenone in the pacing induced canine model of atrial fibrillation (AF).


Mongrel dogs in complete heart block were paced for 1-6 weeks to produce AF, and given KCB-328 or dofetilide. A subset then received propafenone 14+/-3 days after testing the first drug.


KCB-328 prolonged right and left atrial (RA and LA) activation times and AF cycle length (CL), terminating AF in 3 of 6 dogs. RA effective refractory period (ERP) and ventricular ERP and QT interval were prolonged. Dofetilide terminated AF in 1/6 dogs, and increased AF CL and ventricular ERP and QT interval. Dofetilide's reverse use dependency on the QT interval was greater than KCB-328. Propafenone prolonged RA and LA activation times and AF CL and terminated AF in 8 of 9 dogs. One death occurred with dofetilide, none with KCB-328 or propafenone.


The spectrum of effect of the three drugs differed significantly: propafenone showed the greatest success in AF termination, and both propafenone and KCB-328 appeared less proarrhythmic than dofetilide in this model.

[Indexed for MEDLINE]

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