A 72-year-old woman with a history of AF (diagnosed 3 months ago) and hypertension presents with acute-onset severe dyspnea, orthopnea, and chest discomfort. On examination: BP 165/95 mmHg, HR 140 bpm (irregular), RR 28/min, JVP elevated, bilateral basal crackles. ECG confirms AF with RVR. Chest X-ray shows pulmonary edema. Troponin is mildly elevated. Which is the most appropriate immediate intervention?