A 68-year-old woman is seen in the office for a routine health maintenance examination. She complains of intermittent chest pain. She has a history of a prior myocardial infarction and moderate hypertension. Her pulse is 76/min and blood pressure is 150/100 mmHg. Cardiac examination shows a regular rate and rhythm with no murmurs. An electrocardiogram (ECG) shows a normal-appearing P wave and PR interval, a QRS duration of 150 milliseconds, a notched R wave in leads I, AVL, V5 and V6, and the absence of a Q wave in leads I, V5 and V6.

Which of the following is the most likely diagnosis?