Ms. Smith, a 73-year-old female patient, who lives at home i…

Ms. Smith, a 73-year-old female patient, who lives at home independently. Her only chronic health problem is hypertension, diagnosed 2 years ago, which has been well controlled. Ms. Smith is complaining of worsening shortness of breath on her daily walks, starting about 3 weeks ago. She came into urgent care today, as yesterday she also has some accompanying left shoulder & jaw discomfort. Symptoms always stop or resolve within several minutes after she sits down to rest.  She is pain free, with no other symptoms, at the time of her urgent care visit. This history is most consistent with which of the following differential diagnoses?