A 38 years old patient presents with sudden onset chest palpitations which started last week. He has immigrated to United States from southeast Asia. BP is 140/80 mmHg, temperature is 37.5C, heart rate is 115/min & respiratory rate of 13/min. Family history is not available and personal history is positive for intermittent asthma. Chest x-ray is clear & ECG of the patient is attached. Which of the following can be used for the long-term treatment of this patient’s palpitations?

A) Adenosine

B) Warfarin

C) Verapamil

D) Propranolol

E) Flecainide