What are the next best steps for a 73-year-old female with a history of Coronary Artery Disease (CAD) status post Percutaneous Coronary Intervention (PCI) to Left Anterior Descending (LAD) artery, with a recent nuclear stress test showing no evidence of ischemia but a Transient Ischemic Dilation (TID) ratio of 1.45, who is scheduled for right knee surgery?

Management of Elevated TID Ratio Before Knee Surgery

This patient can proceed directly to knee surgery without further cardiac testing or intervention, as she has no evidence of ischemia on stress testing and the isolated TID finding does not change perioperative management. 1

Understanding the Clinical Context

Your patient presents with:

• History of CAD with prior PCI to LAD
• Normal perfusion on SPECT imaging (no ischemia)
• TID ratio of 1.45 (mildly elevated; abnormal is typically >1.22)
• Scheduled for intermediate-risk orthopedic surgery (knee replacement)

The key finding is the absence of stress-induced ischemia despite the elevated TID ratio. 1

Interpretation of Stress Test Results

According to ESC/ESA guidelines, patients without stress-induced ischemia—or with mild-to-moderate ischemia suggestive of one- or two-vessel disease—can proceed to the planned surgical procedure. 1

Your patient falls into the "no ischemia" category, which is the critical determinant for surgical clearance, not the TID ratio alone. 1

Why TID Alone Should Not Delay Surgery

• TID reflects left ventricular cavity dilation during stress and can indicate severe/extensive CAD, but it is not a standalone contraindication to surgery when perfusion is normal 1
• The absence of perfusion defects indicates no significant flow-limiting coronary disease requiring intervention 1
• Routine coronary revascularization before noncardiac surgery does not reduce perioperative risk and should not be performed without specific indications independent of the planned surgery 1, 2

Recommended Next Steps

1. Optimize Medical Therapy (Class I Recommendation)

Ensure the patient is on guideline-directed medical therapy: 1, 3

• Statin therapy: Should be continued or initiated at least 2 days (ideally 30 days) before surgery with long-acting formulations 1, 4
• Aspirin: Continue at 75-100 mg daily unless contraindicated 1
• Beta-blocker: If already taking, continue perioperatively; if not currently on beta-blocker and patient has known ischemic heart disease, consider initiating low-dose therapy 2-30 days before surgery, titrating to heart rate 60-70 bpm with systolic BP >100 mmHg 1, 3
• ACE inhibitor or ARB: Should be held on the morning of surgery and restarted only after confirming euvolemia postoperatively 3

2. Proceed with Surgery as Scheduled

The patient meets criteria to proceed directly to surgery: 1

• Knee replacement is intermediate-risk surgery (1-5% cardiac risk)
• No evidence of unstable cardiac conditions (recent MI within 30 days, decompensated heart failure, significant arrhythmias, severe valvular disease) 1
• No stress-induced ischemia on noninvasive testing 1

3. Perioperative Monitoring Plan

Implement enhanced perioperative cardiac monitoring: 1, 3

• Intraoperative ST-segment monitoring is reasonable for patients with known CAD undergoing noncardiac surgery 1
• Postoperative troponin measurement if ECG changes or chest pain develop 1
• Close attention to hemodynamic management, avoiding both hypotension and excessive fluid administration 3

What NOT to Do (Common Pitfalls)

Do not order coronary angiography or additional stress testing. 1 The patient has no high-risk features on stress testing that would warrant invasive evaluation. Coronary revascularization before noncardiac surgery does not improve outcomes in stable patients. 1, 2

Do not delay surgery for "cardiac optimization" beyond ensuring appropriate medical therapy. 1 The patient is already stable from a cardiac standpoint with no ischemia.

Do not start high-dose beta-blocker therapy acutely (within 2 days of surgery). 1, 2 High-dose beta-blockers administered 2-4 hours before surgery increase stroke risk (1.0% vs 0.5%) and mortality (3.1% vs 2.3%). 2

Do not routinely discontinue aspirin perioperatively. 1, 5 Continue aspirin through the perioperative period unless the surgeon specifically requests discontinuation due to bleeding concerns. 1

Evidence Strength and Nuances

The recommendation to proceed with surgery is based on Class I, Level A evidence from ESC/ESA guidelines stating that patients without stress-induced ischemia can proceed to planned surgery. 1

The TID ratio, while elevated, does not override the absence of perfusion defects. 1 TID can be elevated due to balanced ischemia, microvascular disease, or technical factors, but in the absence of perfusion abnormalities and with prior revascularization of the LAD, this finding alone does not indicate high-risk anatomy requiring intervention. 1

The 2024 AHA/ACC guidelines confirm that stress testing before noncardiac surgery should only be performed if results would change management, and routine revascularization does not reduce perioperative events. 1

Documentation for Surgical Team

Provide clear communication to the surgical and anesthesia teams: 1, 3

• Patient has known CAD, status post PCI to LAD
• Recent stress test shows no inducible ischemia
• Patient is optimized on medical therapy
• Recommend continuation of aspirin and statin perioperatively
• Hold ACE inhibitor/ARB on morning of surgery
• Request enhanced perioperative cardiac monitoring