Internal Medicine · Year 3 · from Internal Medicine

Case 1: Preoperative Cardiovascular Risk Assessment

Patient Presentation

A 68-year-old man with a history of coronary artery disease (stents placed 8 months ago on dual antiplatelet therapy), type 2 diabetes, and hypertension is scheduled for elective right total hip replacement. He walks 2 blocks on flat ground without symptoms but gets short of breath climbing a flight of stairs. He had an MI 2 years ago and underwent PCI with drug-eluting stents. Current medications include aspirin 81 mg, clopidogrel 75 mg, metoprolol 50 mg BID, lisinopril 20 mg, atorvastatin 40 mg, and metformin 1000 mg BID.

Vital Signs

  • Blood Pressure: 138/82 mmHg
  • Heart Rate: 68 bpm
  • Respiratory Rate: 14/min
  • Oxygen Saturation: 98% on room air

Physical Examination

  • General: Well-appearing
  • Cardiovascular: Regular rhythm, no murmurs, no JVD
  • Pulmonary: Clear
  • Extremities: No edema, right hip pain with movement

Recent Studies

  • ECG: Normal sinus rhythm, Q waves in V1-V3 (old MI)
  • Echocardiogram (6 months ago): EF 50%, mild anterior wall hypokinesis
  • Hemoglobin A1c: 7.2%
  • Creatinine: 1.1 mg/dL

Clinical Image

Figure 1: Revised Cardiac Risk Index (RCRI) calculator for perioperative cardiovascular risk assessment.

Image Source: Educational illustration for teaching purposes.

Questions

  1. Calculate this patient's Revised Cardiac Risk Index (RCRI) score. What does it indicate?
  • A) Score 0-1 = low risk
  • B) Score 2 = intermediate risk
  • C) Score 3-4 = high risk
  • D) Score ≥5 = prohibitive risk
  1. What is the recommended management of antiplatelet therapy for this patient?
  • A) Stop both aspirin and clopidogrel 7 days before surgery
  • B) Continue aspirin; stop clopidogrel 5-7 days before surgery if >6 months post-DES
  • C) Continue both through surgery
  • D) Bridge with heparin
  1. Should this patient undergo preoperative cardiac stress testing?
  • A) Yes, all cardiac patients need stress testing
  • B) Only if functional capacity is <4 METs AND RCRI ≥3 AND it will change management
  • C) No, if stable CAD and adequate functional capacity
  • D) Only if EF <40%
  1. What is the perioperative management of metformin?
  1. What beta-blocker management is recommended?

Answers

  1. RCRI calculation (1 point each):
  • High-risk surgery (intraperitoneal, intrathoracic, suprainguinal vascular): No (orthopedic = intermediate risk)
  • Ischemic heart disease: Yes (+1)
  • History of CHF: No
  • History of cerebrovascular disease: No
  • Diabetes on insulin: No (on metformin)
  • Creatinine >2 mg/dL: No
  • Total: 1 point = low risk (estimated major cardiac event risk ~1%)
  1. B) Continue aspirin; stop clopidogrel 5-7 days before surgery if >6 months post-DES - Guidelines:
  • After DES, dual antiplatelet therapy (DAPT) required for minimum 6 months
  • For elective surgery after 6 months: Continue aspirin, hold P2Y12 inhibitor 5-7 days
  • High bleeding risk surgery may require holding both
  • Bare metal stent: Minimum 1 month of DAPT before elective surgery
  • Never stop DAPT within first month post-stent (high stent thrombosis risk)
  1. C) No, if stable CAD and adequate functional capacity - Stress testing approach:
  • Assess functional capacity: Can climb 1 flight of stairs = ≥4 METs
  • This patient has ≥4 METs functional capacity
  • If functional capacity adequate and stable CAD, proceed to surgery without testing
  • Stress testing only if: poor functional capacity (<4 METs) AND elevated risk AND results would change management
  1. Metformin perioperative management:
  • Hold metformin on day of surgery and for 48 hours postoperatively
  • Resume once eating normally AND stable renal function confirmed
  • Concern: Risk of lactic acidosis with contrast exposure, hypoperfusion, or AKI
  • Monitor glucose; use insulin sliding scale as needed perioperatively
  1. Beta-blocker management:
  • Continue beta-blockers in patients already taking them (abrupt withdrawal increases cardiac risk)
  • Do NOT start beta-blockers on day of surgery
  • If initiating beta-blocker for heart rate/BP control, start 2-7 days before surgery and titrate
  • Target heart rate 60-80 bpm; avoid bradycardia and hypotension

All cases for this lecture as Markdown