RT Book, Section A1 Harvey, Robert D. A1 Grant, Augustus O. A2 Katzung, Bertram G. A2 Vanderah, Todd W. SR Print(0) ID 1176970585 T1 Agents Used in Cardiac Arrhythmias T2 Basic & Clinical Pharmacology, 15e YR 2021 FD 2021 PB McGraw-Hill PP New York, NY SN 9781260452310 LK accessmedicine.mhmedical.com/content.aspx?aid=1176970585 RD 2024/04/20 AB CASE STUDYA 69-year-old retired teacher presents with a 1-month history of palpitations, intermittent shortness of breath, and fatigue*. She has a history of hypertension. An electrocardiogram (ECG) shows atrial fibrillation with a ventricular response of 122 beats/min (bpm) and signs of left ventricular hypertrophy. She is anticoagulated with rivaroxaban and started on sustained-release metoprolol, 50 mg/d. After 7 days, her rhythm reverts to normal sinus rhythm spontaneously. However, over the ensuing month, she continues to have intermittent palpitations and fatigue. Continuous ECG recording over a 48-hour period documents paroxysms of atrial fibrillation with heart rates of 88–114 bpm. An echocardiogram shows a left ventricular ejection fraction of 38% (normal ≥60%) with no localized wall motion abnormality. At this stage, would you initiate treatment with an antiarrhythmic drug to maintain normal sinus rhythm, and if so, what drug would you choose?