# Risk Assessment for Perioperative Cardiac Evaluation — ACC/AHA 2014

## Revised Cardiac Risk Index (RCRI / Lee Index)

The RCRI, originally derived and validated by Lee et al. in 1999, is one of the most widely used tools for predicting perioperative cardiac risk in patients undergoing noncardiac surgery. The 2014 ACC/AHA guideline endorses its use as a validated risk-prediction tool for estimating perioperative risk of major adverse cardiac events (MACE). (Class IIa, Level of Evidence: B)

### Six RCRI Risk Factors

Each factor receives 1 point. The total score ranges from 0 to 6.

| Risk Factor | Definition |
|---|---|
| **1. High-risk surgery** | Intraperitoneal, intrathoracic, or suprainguinal vascular surgery |
| **2. History of ischemic heart disease** | History of myocardial infarction, positive exercise test, current chest pain considered due to ischemia, use of nitrate therapy, or ECG with pathological Q waves |
| **3. History of congestive heart failure** | History of CHF, pulmonary edema, paroxysmal nocturnal dyspnea, bilateral rales or S3, or chest radiograph showing pulmonary vascular redistribution |
| **4. History of cerebrovascular disease** | History of transient ischemic attack (TIA) or stroke |
| **5. Diabetes mellitus requiring preoperative insulin therapy** | Preoperative treatment with insulin |
| **6. Preoperative renal insufficiency** | Preoperative serum creatinine > 2.0 mg/dL (> 177 micromol/L) |

> **OpenMedicine Calculator:** `calculate_rcri` -- available via MCP for automated RCRI scoring.

### Estimated Risk of Major Cardiac Events by RCRI Score

| RCRI Score | Estimated Risk of Major Cardiac Complications |
|---|---|
| **0 risk factors** | 0.4% to 0.5% |
| **1 risk factor** | 0.9% to 1.3% |
| **2 risk factors** | 4% to 7% |
| **>= 3 risk factors** | 9% to 11% |

- In the original derivation cohort (n = 2893), rates of major cardiac complications were 0.5%, 1.3%, 4%, and 9% for 0, 1, 2, and >= 3 factors, respectively.
- In the validation cohort (n = 1422), rates were 0.4%, 0.9%, 7%, and 11%.
- Major cardiac complications in the Lee study included myocardial infarction, pulmonary edema, ventricular fibrillation or primary cardiac arrest, and complete heart block.

### Clinical Application in the 2014 Algorithm

- **RCRI 0**: Low risk (< 1% MACE) -- proceed to surgery without further testing (Step 4).
- **RCRI >= 1**: May indicate elevated risk (>= 1% MACE) depending on surgical risk -- proceed to functional capacity assessment (Step 5).
- **RCRI >= 3**: Associated with significantly elevated cardiac risk (9-11%). These patients are candidates for consideration of perioperative beta-blocker initiation (Class IIb, Level of Evidence: B).

## Other Endorsed Risk-Prediction Tools

### ACS NSQIP MICA Calculator

The American College of Surgeons National Surgical Quality Improvement Program Myocardial Infarction and Cardiac Arrest (NSQIP MICA) calculator uses procedure-specific data from a large national database. It incorporates:
- Type of surgery (21 specific procedure categories)
- Dependent functional status
- ASA class
- Creatinine > 1.5 mg/dL
- Age

### ACS NSQIP Surgical Risk Calculator

The broader NSQIP Surgical Risk Calculator predicts multiple adverse outcomes, including cardiac complications, using patient and procedure-specific variables.

## Surgical Risk Categories

The 2014 guideline simplified the previous 3-tier surgical risk classification (low, intermediate, high) into a 2-tier system:

### Low-Risk Surgery (< 1% Risk of MACE)

Procedures with a combined surgical and patient risk of MACE < 1%:
- Cataract surgery
- Other ophthalmologic procedures
- Superficial procedures
- Endoscopic procedures
- Ambulatory surgery
- Breast surgery

### Elevated-Risk Surgery (>= 1% Risk of MACE)

Procedures with a combined surgical and patient risk of MACE >= 1%:
- Intraperitoneal surgery
- Intrathoracic surgery
- Major vascular surgery (suprainguinal vascular: aortic, major peripheral vascular)
- Head and neck surgery
- Orthopedic surgery (e.g., hip, spine)
- Prostate surgery
- Carotid endarterectomy
- Peripheral arterial angioplasty

Note: The combined clinical/surgical risk determines the category. A patient undergoing very low-risk surgery (e.g., ophthalmologic) even with multiple risk factors would generally have a low risk of MACE, whereas a patient undergoing major vascular surgery with few risk factors would have an elevated risk.

## Functional Capacity Assessment

Functional capacity is a key determinant of perioperative risk in patients with elevated surgical risk:

### Assessment Methods

1. **Clinical history** -- Ask about the ability to perform activities of daily living expressed in metabolic equivalents (METs).
2. **Duke Activity Status Index (DASI)** -- A 12-item questionnaire that objectively estimates functional capacity.
3. **Exercise tolerance testing** -- If functional capacity cannot be determined clinically.

### MET Categories

| Category | METs | Clinical Significance |
|---|---|---|
| **Poor** | < 4 METs | Associated with increased perioperative cardiac and long-term risk |
| **Moderate** | 4 to < 7 METs | Adequate for most daily activities; reassuring for surgical clearance |
| **Good** | 7 to 10 METs | Vigorous activity capacity |
| **Excellent** | > 10 METs | Strenuous sports-level activity |

### Decision Threshold

- **>= 4 METs**: Proceed to surgery without further cardiac testing, even if elevated risk. (Class IIa, Level of Evidence: B)
- **< 4 METs or unknown**: Consider whether further testing will change management (Steps 6 and 7 of the algorithm).

## Biomarkers for Risk Assessment

### Preoperative Troponin

- The guideline does not recommend routine preoperative troponin measurement for risk stratification in patients undergoing noncardiac surgery.

### B-type Natriuretic Peptide (BNP)

- Measurement of BNP or NT-proBNP may be reasonable for obtaining preoperative risk assessment in patients undergoing elevated-risk noncardiac surgery. (Class IIb, Level of Evidence: B)

## Limitations

- The RCRI was derived and validated in elective major noncardiac surgery in a single tertiary-care center. Its performance may vary in other populations.
- The RCRI may underestimate risk in certain high-risk surgical populations, particularly vascular surgery patients.
- Functional capacity assessment by history has limited sensitivity and specificity; self-reported activity levels can be unreliable.
- The ACS NSQIP calculators may provide more procedure-specific risk estimates than the RCRI, but require procedure-specific coding.
- The 2-tier (low vs. elevated) risk stratification simplifies clinical decision making but eliminates the previous distinction between intermediate and high surgical risk.
