This patient should take his β-blocker, metoprolol, the morning of surgery. He takes three chronic medications, of which two are normally taken in the morning. All medications should be continued uninterrupted throughout surgery unless potential adverse effects from continuation outweigh benefits. Not only is metoprolol important for treatment of his hypertension, but withdrawal of β-blockade in the perioperative setting may cause tachycardia and increased myocardial oxygen demand. The American College of Cardiology (ACC) and the American Heart Association (AHA) provide a level 1 recommendation for the continuation of β-blockers throughout the perioperative period. Thus, metoprolol should be taken the morning of surgery.

Metformin has the potential for causing lactic acidosis and inducing hypoglycemia if taken during fasting. Therefore, it should not be taken on the morning of surgery. Some experts advise withholding this medication for 24 to 48 hours before surgery, although data for the specific withholding timeframe are limited.

The ACC and AHA recommend that for patients currently taking a statin and scheduled for noncardiac surgery, the statin should be continued. This recommendation is based on several systematic reviews that found an association between perioperative statin use and a reduction in postoperative acute coronary syndrome and mortality. This patient should resume his statin therapy in the evening following his operation, maintaining his usual schedule.