Dofetilide works by selectively blocking the rapid component of the delayed rectifier outward potassium current (IKr).

This causes the refractory period of atrial tissue to increase, hence its effectiveness in the treatment of atrial fibrillation and atrial flutter.

Dofetilide does not affect dV/dTₘₐₓ (the slope of the upstroke of phase 0 depolarization), conduction velocity, or the resting membrane potential.

There is a dose-dependent increase in the QT interval and the corrected QT interval (QTc).
 Because of this, many practitioners will initiate dofetilide therapy only on individuals under telemetry monitoring or if serial EKG measurements of QT and QTc can be performed.
Dofetilide works by selectively blocking the rapid component of the delayed rectifier outward potassium current (IKr).
This causes the refractory period of atrial tissue to increase, hence its effectiveness in the treatment of atrial fibrillation and atrial flutter.
Dofetilide does not affect dV/dTₘₐₓ (the slope of the upstroke of phase 0 depolarization), conduction velocity, or the resting membrane potential.
There is a dose-dependent increase in the QT interval and the corrected QT interval (QTc).  Because of this, many practitioners will initiate dofetilide therapy only on individuals under telemetry monitoring or if serial EKG measurements of QT and QTc can be performed.
Dofetilide