MARKED QRS PROLONGATION FROM FLECAINIDE DURING EXERCISE STRESS TESTING

Flecainide is commonly used for atrial fibrillation. Caution is advised due to its risk of proarrhythmia. If there is a > 15% - 20% increase in the QRS duration at resting heart rate, the dose should be reduced. An exercise stress test should be performed, to make sure the QRS does not increase