Why digoxin is absolutely contraindicated in a case of ventricular fibrillation?

Let me help myou. Digoxin is a heart stimulant with a very narrow range of safe doses. Ventricular tachycardia is very common adverse side effect of digoxin, and would likely make this condition worse or increase the frequency of the episodes. Stimulating a heart that is already beating too fast (tachycardia) could be fatal. Good luck.
Ventricular fibrill. Digoxin can cause life threatening ventricular arrhythmias so giving it to a patient with one is certainly not a good idea.