A. First step: if the surgery is emergent, no cardiac workup is performed preoperatively

B. Second step: if the surgery is not emergent, evaluate for active cardiac conditions

Active cardiac conditions:

• Active, unstable coronary syndrome, or recent MI (<1 month) with persistent ischemic symptoms or ischemia on non-invasive stress testing
  
• Severe unstable arrhythmia
  
• Decompensated HF
  
• Severely symptomatic valvular heart disease

These patients need to have their cardiac condition treated before surgery, depending on the urgency of the surgery (PCI for ACS, medical therapy for HF, surgical therapy for symptomatic, severe valvular disease).

In case of an emergent surgery, proceed to the high-risk surgery with maximal medical therapy.

C. Third step: in the absence of active cardiac conditions, look for clinical risk factors, and use the revised cardiac risk index or Lee index

The Lee index includes six factors:⁵

• History of CAD
  
• Compensated or prior HF
  
• Diabetes
  
• Renal insufficiency with creatinine >2 mg/dl
  
• Cerebrovascular disease
  
• Intermediate- or high-risk surgery
  
  
  
  1. In the case of a Lee risk score of 0 to 2, or in the case of a low-risk surgery regardless of risk factors, surgery is performed without any further cardiac workup. The surgery is a low-cardiac-risk surgery.
     
  2. In the case of a Lee risk score ≥3 and poor functional capacity <4 METs (or unknown) and intermediate- or high-risk surgery, non-invasive preoperative cardiac testing may be performed for further cardiac risk assessment (class IIa recommendation). If the functional capacity is ≥4 METs, especially ≥7 METs, stress testing is not needed even if the Lee risk score is high. Preoperative testing determines the functional capacity when it is unclear (exercise testing), and allows risk stratification of patients with a clearly reduced functional capacity <4 METs (pharmacologic testing). Four METs correspond to climbing 2 flights of stairs, walking up a hill, walking fast at ground level, dancing, or performing heavy housework or yardwork (pushing a power mower, scrubbing floors, carrying heavy groceries). Sexual intercourse corresponds to 3–5 METs.

Note that preoperative testing is mainly useful to assess how risky the surgery will be and to see whether it should be avoided or altered, if possible. Testing is only performed if it will change management, i.e., if surgery can be deferred. Preoperative testing is, therefore, much less useful in patients who require a necessary, vital surgery (e.g., cancer surgery).

A high-risk finding on preoperative testing indicates preoperative coronary angiography only if preoperative revascularization is feasible, i.e., surgery can be deferred and the patient can tolerate an antithrombotic regimen. If extensive CAD is present (left main or multivessel CAD), revascularization, typically CABG, should generally be performed before a non-vital elective surgery (class I recommendation). This revascularization is mainly meant to improve the long-term cardiac risk of the patient. Outside ACS or left main disease, preoperative revascularization does not clearly change the operative cardiac risk (CARP trial), even in high-risk ischemic patients with at least five abnormal segments on stress imaging (LV being divided into 17 segments).^5,6 There is no evidence that PCI of a single- or two-vessel disease improves perioperative outcomes, outside ACS.

A. Classification of the surgery’s risk

The surgery is classified into one of three risk categories:

• High risk: aortic or major peripheral vascular surgery
  
• Intermediate risk: intraperitoneal, intrathoracic, carotid endarterectomy, common femoral endarterectomy, head and neck surgery, orthopedic surgery, prostate surgery
  
• Low risk: endoscopic procedures, breast surgery, cataract surgery, ambulatory surgery

The risk of perioperative major cardiac events (death or MI) is generally ≤1% with low-risk surgery, regardless of the underlying patient’s risk; and is generally 1–5% with intermediate-risk surgery and 5% with high-risk surgery, although the actual risk of intermediate- and high-risk surgeries also depends on the patient’s intrinsic risk (Lee risk score). For example, a low-risk patient undergoing major vascular surgery has <2–5% risk of major cardiac events.

B. Classification of the patient’s overall risk (integrates the surgery’s risk with the patient’s risk factors)

In the presence of an active cardiac condition (Section I.B, above), the patient is a high-risk patient.

In the absence of an active condition, a Lee risk score ≥3 identifies high-risk stable patients, a score of 2 identifies intermediate-risk patients, while a score of 0 or 1 identifies low-risk patients. The risk of postoperative major adverse cardiac events (MACE) (MI, VF or primary cardiac arrest, or definite pulmonary edema) in high-, intermediate-, and low-risk patients is ≥9%, 4–5%, and 0.5–1.3%, respectively.⁷

Caveats

1. Only 35% of CARP patients had three-vessel CAD and only 44% had moderate/large ischemia on stress testing. At least 25% had low-risk Lee score and nuclear imaging.⁶ In a post-hoc analysis of CARP, patients who underwent CABG had similar mortality but fewer MIs after vascular surgery than those who underwent PCI and probably those treated medically, despite the more extensive CAD in CABG patients.⁸ In another CARP analysis, patients with large anterior ischemia seemed to benefit from preoperative revascularization.⁹ This underlines a potential role of preoperative CABG in patients with extensive CAD undergoing elective vascular surgery.
   
2. Left main disease was excluded from the CARP trial, and, in an analysis of the CARP registry, left main disease benefited from preoperative revascularization.¹⁰

Preoperative coronary testing may be useful to show the general prognosis of the patient. A high surgical risk based on preoperative stress testing may lead to a change in management but not necessarily revascularization. It should lead to a risk/benefit discussion with the patient, with a potential cancellation of non-vital surgery and consideration of percutaneous angioplasty for PAD or endovascular repair of abdominal aortic aneurysm, even if the result is expected to be inferior to surgery. Preoperative coronary testing is much less useful in patients who require a vital surgery, such as cancer surgery.