This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Pharmacology
Digoxin toxicity produce all of the changes in ECG except 
Select and explain. 
A. Inveed T waves, B. Prolonged QT interval, C. ST depression, D. Prolonged PR interval
B: Prolonged QT interval
Answer: B: Prolonged QT interval 
Explanation: In digoxin toxicity, the finding of frequent premature ventricular beats (PVCs) is the most common and the earliest dysrhythmia. Sinus bradycardia is also very common. In addition, depressed conduction is a predominant feature of digoxin toxicity. Other ECG changes that suggest digoxin toxicity include bigeminal and trigeminal rhythms, ventricular bigeminy, and bidirectional ventricular tachycardia.[ Refer kDT 7/e p514