Mr. Tom Winters recently sustained a myocardial infarction (…

Mr. Tom Winters recently sustained a myocardial infarction (MI) and has been referred to physical therapy for a strengthening and conditioning program.  The PTA noted on the initial physical therapy examination that the patient is on Beta-Blockers.  In addition to the ‘rate of perceived exertion’, which of the following vital signs would provide the most accurate assessment?