This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
[{'content': 'In making your decision to treat with procainamide, which of the following statements would be relevant? \nSelect and explain. \nA. Procainamide may worsen or precipitate hypehyroidism, B. Procainamide is not effective for atrial arrhythmias, C. Procainamide prolongs the effective refractory period in atrial and ventricular cells, D. Procainamide commonly induces thrombocytopenia', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Procainamide prolongs the effective refractory period in atrial and ventricular cells. Ref: KDT, tth Edition, Page 511,512 Procainamide prolongs refractory period by blocking sodium channels and by prolonging the AP. All of the other statements are false.', 'role': 'assistant'}]