What is the role of scoring systems like EuroSCORE (European System for Cardiac Operative Risk Evaluation) or STS (Society of Thoracic Surgeons) score in CABG (Coronary Artery Bypass Grafting) preparation?

Role of Scoring Systems in CABG Preparation

The STS risk score is recommended as the primary scoring system for patient risk stratification in CABG preparation, as it provides excellent predictive value for estimating risk of death and major morbidities based on clinical factors. 1

Importance of Risk Scoring in CABG Decision-Making

Risk scoring systems play several critical roles in CABG preparation:

1. Risk Stratification:

   • STS risk score helps quantify the risk of mortality and major morbidities for individual patients
   • Provides objective data to inform the Heart Team's decision-making process
   • Facilitates informed consent discussions with patients 1

2. Treatment Strategy Selection:

   • Helps determine whether surgical (CABG) or percutaneous revascularization is most appropriate
   • Supports the Heart Team approach, which includes primary cardiologist, interventional cardiologist, and cardiac surgeon 1

Comparison of Risk Scoring Systems

STS Risk Score

• Advantages:
  • Based on 24 covariates from 67,292 patients undergoing isolated AVR in the US (2002-2006)
  • Periodically updated (most recent update in 2018)
  • Excellent predictive value for adverse events
  • Superior performance at higher (>5%) predicted mortality rates 1
  • Better discrimination than EuroSCORE II for CABG patients 1, 2

EuroSCORE II

• Advantages:
  • Based on 12 covariates
  • Simpler to calculate than STS score
  • Good predictive value for lower-risk patients
• Limitations:
  • Less accurate than STS for CABG patients, particularly at higher risk levels
  • May underestimate risk in high-risk patients (>12% risk) 3

Clinical Application in CABG Preparation

1. Heart Team Approach:

   • Risk scores should be calculated and discussed within a multidisciplinary Heart Team
   • Team should include interventional cardiology, cardiac surgery, and non-invasive cardiology specialists 1
   • Risk scores inform but do not replace clinical judgment 1

2. Decision-Making Process:

   • Calculate STS risk score for all patients being considered for CABG (Class I recommendation, Level B-NR) 1
   • Consider both anatomical complexity (e.g., SYNTAX score) and patient-specific risk factors
   • Use risk scores to guide discussions about revascularization options 1

3. Informed Consent:

   • Share risk score results with patients to facilitate informed decision-making
   • Discuss predicted mortality and morbidity risks based on objective data 1

Limitations of Risk Scoring Systems

• Incomplete Risk Assessment:

  • Both STS and EuroSCORE II have limited ability to assess certain risk factors:
    • Frailty
    • Liver cirrhosis
    • Malnutrition
    • Porcelain aorta 1
  • Additional assessment tools may be needed for these factors

• Calibration Issues:

  • Risk models may over-predict mortality in low-risk patients and under-predict in high-risk patients 3
  • Performance may vary across different populations and centers 4

Best Practices for Using Risk Scores

1. Use STS score as primary risk assessment tool for CABG patients 1

2. Avoid excluding patients from surgery based solely on a single high-risk characteristic 1

3. Incorporate risk scores into a comprehensive evaluation that includes:

   • Clinical judgment
   • Patient preferences
   • Anatomical considerations (e.g., SYNTAX score for complex CAD) 1

4. Consider additional assessment tools for factors not captured by standard risk scores (frailty, liver disease) 1

5. Use risk scores to guide post-operative management planning, including preventive strategies for complications like atrial fibrillation 1, 5

Risk scoring systems are valuable tools in CABG preparation, but they should be used as part of a comprehensive Heart Team approach that combines objective risk assessment with clinical expertise and patient-centered decision-making.