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': 'Normal asymptomatic case of myocardial infarction previously treated with antiplatelet and thrombolytic therapy. Secondary prophylaxis for this patients with \nSelect and explain. \nA. Beta - blockers, B. Calcium channel blockers, C. Nitrates, D. Aldosterone antagonists', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (Beta- blockers) (324- CMDT-08) (1543-H17th)Secondary prevention of MI* b -blockers improve survival rates, primarily by reducing the incidence of sudden death in high -risk subjects of patients through their value may be less in patients without complications with small infection and normal exercise tests* b -blockade should be avoided in patients with decompensated heart failure, decompensated asthma or high degrees of AV block* Antiplatelet agent - aspirin and clopidogrel are recommended', 'role': 'assistant'}]