A 38-year-old woman without prior cardiac history presents to the emergency department with acute-onset palpitations and dyspnea. She reports symptom onset 15 minutes ago while at rest. Vital signs: BP 128/82 mmHg, HR 165 bpm, RR 18/min, O2 saturation 98% on room air. Physical examination reveals a regular pulse and no murmurs. A 12-lead ECG demonstrates a wide-complex tachycardia with left bundle branch block morphology. Chest X-ray is normal. Laboratory studies including electrolytes, troponin, and TSH are all within normal limits. Intravenous adenosine 6 mg is administered with no effect on the arrhythmia. The patient remains hemodynamically stable with adequate perfusion. Which of the following is the most appropriate next intervention?

1. A)Intravenous verapamil 5 mg bolus
2. B)Intravenous diltiazem followed by transesophageal pacing
3. C)Intravenous procainamide followed by consideration of synchronized cardioversion if rhythm does not terminateGABARITO
4. D)Urgent electrophysiology consultation for immediate ablation
5. E)Observation with continuous cardiac monitoring and serial ECGs