Which medication should not be used to treat Wolff-Parkinson-White syndrome?

The most appropriate medication to avoid in the treatment of Wolff-Parkinson-White (WPW) syndrome is digoxin. In patients with WPW, digoxin can potentially exacerbate arrhythmias due to the presence of an accessory pathway. Digoxin increases atrioventricular (AV) node conduction while potentially facilitating conduction through the accessory pathway, which can lead to accelerated conduction and worsen tachyarrhythmias like atrial fibrillation.

In contrast, beta-blockers, amiodarone, and calcium channel blockers can generally be used cautiously in managing WPW syndrome, particularly to control ventricular rates during atrial fibrillation or other tachyarrhythmias. Beta-blockers can help decrease heart rate and manage symptoms, amiodarone is effective in controlling arrhythmias including those caused by WPW, and certain calcium channel blockers, while needing careful use, can also be useful in some WPW-related arrhythmias.

Therefore, digoxin is specifically contraindicated due to its potential to cause or exacerbate life-threatening arrhythmias in patients with WPW syndrome.