flecainide
Meaning of flecainide: A rhythm-control drug rather than a rate-control one, limited to hearts without structural disease because of a documented safety concern.
Definition of flecainide
Flecainide is an antiarrhythmic medication used to restore and maintain a normal heart rhythm in certain rapid, disorganized rhythms, including some forms of atrial fibrillation. It blocks sodium channels in heart muscle cells, which slows the electrical impulse that triggers each beat. It is largely reserved for people whose hearts are otherwise structurally normal.
How does it steady a heart rhythm?
Every heartbeat begins as an electrical impulse that sweeps across the heart muscle. Sodium rushing into the muscle cells is what makes that impulse rise sharply and travel quickly. Flecainide blocks the channels sodium moves through, so the impulse rises more slowly and spreads more slowly through the tissue. Rapid, disorganized rhythms depend on signals circling through the muscle fast enough to keep reentering tissue that has just recovered. Slowing conduction makes that circuit harder to sustain, and the heart is more likely to hold a steady, coordinated pattern of contraction. Within the antiarrhythmic classes defined by this sodium-channel effect, flecainide is among the strongest at slowing conduction.
Why does structural heart disease change the picture?
Heart muscle that has been scarred by a previous heart attack, thickened, or weakened does not conduct evenly. Adding a drug that slows conduction further can turn an irregular but survivable rhythm into a dangerous one, an effect called proarrhythmia. A large trial that tested flecainide and similar drugs in people recovering from a heart attack was stopped early because more deaths occurred in the treated group than in the group given placebo. That result reshaped how the whole class is used and is the reason the following distinctions are drawn so firmly.
| Setting | How flecainide is regarded |
|---|---|
| Structurally normal heart | An accepted option for holding a normal rhythm |
| Prior heart attack or scarred muscle | Avoided, given the higher risk of a dangerous rhythm |
| Congestive heart failure or a weakened pumping chamber | Avoided for the same reason |
| Marked thickening of the heart wall | Generally avoided |
What does it not do?
Flecainide does not simply slow a rhythm that has already become disorganized, which is what a rate-control drug does. Its purpose is to restore and hold the normal rhythm itself, so episodes can still break through while it is being taken. It also does nothing about the conditions that promote atrial fibrillation, including high blood pressure, sleep apnea, thyroid disease and heavy alcohol use, each of which is addressed on its own. Because the drug slows conduction throughout the heart, treatment is followed with periodic tracings of the heart's electrical activity rather than by symptoms alone.
Also known as
Used in a sentence
Flecainide was prescribed to help control episodes of atrial fibrillation in the absence of structural heart disease.
Good to know
Flecainide is generally avoided in people with structural heart disease or a prior heart attack, since trial evidence in that population showed a higher risk of the medication provoking a serious rhythm disturbance rather than preventing one.