This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S., Subject name: Medicine
[{'content': 'Digoxin is contraindicated in \nSelect and explain. \nA. Hypertrophic cardiomyopathy, B. Supraventricular tachycardia, C. Congestive heart failure, D. Atrial flutter', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A. i.e. (Hypertrophic cardiomyopathy) (1485 - H17th)Hypertrophic CMP - Digitalis, diuretics, nitrates, dihydropyridine calcium blockers, vasodilators and b- adrenergic agonists are best avoided, particularly in patients with know LV out flow tract pressure gradients - (1485 - H17th)Dose reduction in Digitalis in following conditions* Hypokalemia** Advanced age** Hypomagnesemia* Hypoxia** **Renal failure* Hypothyroidism* Hypercalcemia* Myocarditis* Electrical - cardioversion* Lidocaine is the drug of choice in digoxin induced arrhythmias* **Diuretics & Hemodialysis are NOT used for treatment of digitalis toxicity* Major electrophysiological effect of digitalis1. Hyperpolarization2. Shortening of atrial action potential3. Increase in AV node refractoriness', 'role': 'assistant'}]