What are the recommendations for risk stratification in surgery clearance?

Risk Stratification for Surgery Clearance

Use a structured algorithmic approach combining validated risk calculators (RCRI or NSQIP MICA), functional capacity assessment (≥4 METs threshold), and surgery-specific bleeding risk to stratify patients into actionable risk categories that guide perioperative management decisions. 1

Step 1: Assess for Active Cardiac Conditions Requiring Immediate Intervention

Identify conditions that mandate cancellation or delay of elective surgery 2, 3:

• Unstable coronary syndromes: unstable or severe angina, myocardial infarction within 30 days 2, 3
• Decompensated heart failure: NYHA class IV, new-onset or worsening heart failure 2, 3
• Significant arrhythmias: high-grade AV block, Mobitz II, third-degree heart block, symptomatic ventricular arrhythmias, supraventricular arrhythmias with uncontrolled ventricular rate 3
• Severe valvular disease: severe aortic stenosis, symptomatic mitral stenosis 3

If any active cardiac condition is present, proceed with cardiac evaluation and treatment before surgery. For emergency surgery, proceed with maximal medical therapy and intensive perioperative monitoring 2.

Step 2: Classify Surgical Procedure Risk

Categorize the planned surgery by bleeding risk and cardiac risk 2, 1:

Bleeding Risk Classification 2:

• High-bleed-risk (≥2% 30-day major bleeding): major surgery with extensive tissue injury, cancer resection, major orthopedic surgery, cardiac/intracranial/spinal surgery, any neuraxial anesthesia
• Low-to-moderate-bleed-risk (0-2%): arthroscopy, coronary angiography, laparoscopic cholecystectomy, hernia repair
• Minimal-bleed-risk (~0%): minor dermatologic procedures, cataract surgery, dental cleanings, pacemaker implantation

Cardiac Risk Classification 1:

• Low risk (<1% MACE): superficial procedures, cataract surgery, breast surgery
• Elevated risk (≥1% MACE): intra-abdominal, intrathoracic, vascular, orthopedic procedures

Emergency procedures carry 2-5 times higher risk than elective surgeries 1.

Step 3: Calculate Patient-Specific Cardiac Risk

Apply the Revised Cardiac Risk Index (RCRI) or preferably the NSQIP MICA calculator for superior discrimination 1:

RCRI assigns 1 point for each 1:

• History of ischemic heart disease
• History of compensated or prior heart failure
• History of cerebrovascular disease
• Diabetes mellitus requiring insulin
• Chronic kidney disease (creatinine >2 mg/dL)
• High-risk surgery (intraperitoneal, intrathoracic, suprainguinal vascular)

Risk interpretation: 0 points = 0.4% MACE risk; 1 point = 1% risk; 2 points = 2.4% risk; ≥3 points = 5.4% risk 1.

Step 4: Assess Functional Capacity

Determine metabolic equivalent (MET) capacity using the Duke Activity Status Index (DASI) 1:

• ≥4 METs (can climb 2 flights of stairs, walk uphill, run short distance): lower perioperative risk, proceed to surgery with heart rate control 2, 1
• <4 METs or unknown capacity: higher risk, requires further risk stratification 2, 1

Patients with known cardiac disease who exercise regularly require less extensive evaluation than sedentary patients 3.

Step 5: Determine Need for Additional Testing

For patients with poor functional capacity (<4 METs) and ≥3 clinical risk factors undergoing vascular surgery: consider noninvasive stress testing if it will change management 2.

For patients with poor functional capacity and 1-2 clinical risk factors OR intermediate-risk surgery: proceed with planned surgery with heart rate control; noninvasive testing might be considered only if it will change management 2.

For low-risk procedures: further cardiac testing is not recommended regardless of patient risk factors 1.

Common pitfall: Risk scores have poorer discrimination in vascular surgery patients due to underestimation of MI risk 1. In these patients, consider additional biomarker assessment.

Step 6: Obtain Risk Stratification Biomarkers

For cardiac surgery patients 2:

• Hemoglobin A1c: target <6.5% optimal, <7% acceptable; levels correlate with deep sternal wound infection and long-term survival 2
• Serum albumin: levels <3.0 g/dL predict increased ventilator time, acute kidney injury, infection, and mortality 2
• B-type natriuretic peptide: additional risk stratification factor for cardiac complications 1

For patients with pulmonary arterial hypertension 2:

• Recent (within 3-6 months) transthoracic echocardiogram
• Right heart catheterization data
• Six-minute walk test
• NT-pro BNP levels
• WHO functional class >II, right ventricular hypertrophy, right axis deviation, and higher mean pulmonary artery pressure predict worse outcomes 2

Step 7: Stratify Antithrombotic Risk

For patients on anticoagulation, assess thromboembolism risk 1:

Arterial thromboembolism risk (atrial fibrillation, mechanical valves) 1:

• High risk: >10%/year
• Intermediate risk: 4-10%/year
• Low risk: <4%/year

Venous thromboembolism risk 1:

• High risk: >10%/month
• Intermediate risk: 4-10%/month
• Low risk: <2%/month

Match antithrombotic interruption strategy to combined bleeding and thrombosis risk 2, 1.

Step 8: Identify Additional Modifiable Risk Factors

Screen for and optimize 1:

• Smoking: cessation ≥4 weeks before surgery
• Alcohol: abstinence 4 weeks prior to surgery
• Undiagnosed hypertension and diabetes: screen and optimize
• Anemia: associated with increased perioperative ischemia, especially in vascular surgery 3
• Nutritional deficiency: if albumin <3.0 g/dL, consider 7-10 days intensive nutrition therapy if feasible 2
• Obstructive sleep apnea: use validated screening tool 1

Step 9: Special Population Considerations

Elderly patients 1:

• Perform multidisciplinary assessment with early geriatrician and anesthesiologist involvement
• Evaluate for frailty, which independently predicts perioperative risk
• Assess for delirium risk factors: age, ASA status >2, Charlson Comorbidity Index ≥2
• Avoid relying solely on age; urgency and organ disease carry greater risk

Patients with congenital heart disease 1:

• Single-ventricle patients and unrepaired/palliated cyanotic CHD are at elevated risk
• Assess complexity and severity of disease

Patients with pulmonary hypertension 2:

• Avoid elective surgery unless it dramatically improves quality of life
• Even minor procedures (dental extractions, colonoscopies) require serious consideration due to risk of acute PVR increase
• Morbidity rates 2-42%, mortality rates 1-18% for non-cardiac surgery
• Assemble multidisciplinary team for major cases with cardiac anesthesiologist involvement

Critical Communication Points

Never use the phrase "cleared for surgery" in consultation notes 3. Instead, document specific findings, risk stratification results, and recommendations for perioperative management 3.

Ensure clear communication between consultant, surgeon, anesthesiologist regarding 3:

• Identified risk factors and their severity
• Recommended perioperative monitoring intensity
• Medication management plan
• Postoperative surveillance strategy

The perioperative evaluation represents an opportunity to implement long-term cardiac risk reduction strategies beyond immediate surgical concerns 3.