Q. A 26-year-old man comes to the clinic complaining of recurrent chest pain. The patient mentions that chest pain is always associated with exertion and is relieved spontaneously after rest. The patient is a striker on his college soccer team. He has no significant medical history. His family history is significant of diabetes mellitus on the mother's side and ischemic heart disease on the father's side. He also has an uncle that died suddenly at the age of 35. Vital signs are normal. Cardiac examination reveals an additional late diastolic heart sound. Echocardiography shows concentric left ventricular hypertrophy with predominance in the septal region. Which of the following drugs should be avoided in the above patient?