Antiarrhythmics

A 62-year-old woman with chronic atrial fibrillation is started on amiodarone for rate control. After 3 months of therapy, she develops tremor, ataxia, and cognitive slowing. Which of the following best explains the mechanism of this adverse effect?

A 58-year-old man with a history of hypertension and coronary artery disease presents to the emergency department with palpitations and dyspnea. ECG shows atrial fibrillation with a ventricular rate of 145 bpm. Blood pressure is 110/70 mmHg, and he is haemodynamically stable. Troponin is negative. He has no prior antiarrhythmic therapy. Which of the following is the most appropriate first-line pharmacological agent for rate control in this patient?

A 72-year-old woman with a history of recurrent paroxysmal atrial fibrillation and structural heart disease (ejection fraction 35%) presents for long-term rhythm control. She has had two episodes of AF in the past 3 months despite rate-control therapy. Her renal function is normal (eGFR 65 mL/min/1.73 m²), and baseline QTc is 420 ms. Which antiarrhythmic agent is most appropriate for maintenance rhythm control in this patient?

A 55-year-old man with acute myocardial infarction complicated by recurrent ventricular ectopics is started on intravenous lidocaine. Which of the following best explains why lidocaine is preferred over quinidine in the acute post-MI setting?

A 68-year-old man with a history of dilated cardiomyopathy presents with sustained ventricular tachycardia. He is initiated on intravenous procainamide. Which of the following best explains the antiarrhythmic mechanism of procainamide in this patient?