You prescribe bisoprolol, a beta blocker, as you remember that these drugs may reduce anginal pain because they reduce cardiac output and thus oxygen demand of the heart. A cardioselective beta blocker like bisoprolol is guideline‑preferred for stable angina unless contraindicated and it tackles the supply-demand mismatch that triggers symptoms during activity. You also decide to prescribe sublingual glyceryl trinitrate (GTN, a nitrate), so that Mr. Garcia can use it prior to strenuous activities or during acute episodes.  

Six months later 

Mr Garcia attends his follow-up appointment. His heart rate is 65bpm and his blood pressure 125/85mmHg. Mr Garcia informs you that he feels well on most days. However, you are concerned that the symptoms have not fully resolved, and you think it’s a good idea to add another drug to his regimen.   

Which drug is most appropriate for Mr. Garcia?