This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: CHF, Angina Pectoris and Myocardial Infarction, Subject name: Pharmacology
[{'content': 'Which of the following drug is contraindicated in variant angina? \nSelect and explain. \nA. Diltiazem, B. Nitrates, C. Propranolol, D. Verapamil', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Variant angina is caused by coronary vasospasm DOC:Sublingual Nitroglycerine Prophylaxis : Calcium channel blockers (like verapamil and Diltiazem) and nitrates Beta blockers are avoided as they may precipitate coronary vasospasm by counteracting beta 2 mediated coronary vasodilation. Therefore they are avoided in variant angina.', 'role': 'assistant'}]