A 55 year old male with a history of hypertension presents to the emergency room with acute onset chest pains. His temperature is 37.0, blood pressure 190/70 in the left arm and 150/70 in the right arm, heart rate 110, respirations 22, and oxygen saturation 94% on room air. Physical examination reveals normal lung sounds, elevated jugular venous pressures and a II/IV early diastolic murmur at the right upper sternal border. ECG shows normal sinus rhythm and left ventricular hypertrophy. Which of the following is the most likely diagnosis?