Revised Cardiac Risk index (RCRI)

RCRI is an index to evaluate major cardiac complications for noncardiac surgery. There are 6 risk predictors of RCRI:

1. High risk surgery (e.g., vascular, intrathoracic) (Odds Ratio 2.6)
2. CAD (e.g., hx of MI, PCI, CABG, Angina, nitrate use, ECG with pathological Q wave, or positive stress test) (Odds Ratio 3.8)
3. History of CHF, pulmonary edema, bilateral rales (Odds Ratio 4.3)
4. History of cerebrovascular disease (e.g., stroke or TIA) (Odds Ratio 3)
5. Diabetes mellitus treated with insulin (Odds Ratio 1)
6. Preop Cr > 176.8 µmol/L (Odds Ratio 0.9)

Note that those Odds Ratios above were calculated using multivariable logistic regressions rather than univariate logistic regression. 

The original RCRI article showed event rate as below:

Rate of cardiac death, MI, pulm edema, complete heart block, or VF/cardiac arrest
Number of RCRI Risk factors	Rates of event
0	0.5%
1	1%
2	5%
≥3	10%

The rates of major cardiac complications were later reassessed in 2017 using four data from four prospective studies and one retrospective studies:

Rate of myocardial infarction, cardiac arrest, or death at 30 days after noncardiac surgery
Number of RCRI Risk factors	Rates of event
0	4%
1	6%
2	10%
≥3	15%

The discrepancies were potentially caused by the test method and enrollment criteria. The original study used CK-MB while recent studies used troponin which were more sensitive. Additionally, the original study excluded emergency surgery patients while recent studies included patients who received emergency surgeries. 

Reference:

Multifactorial index of cardiac risk in noncardiac surgical procedures - PubMed (nih.gov)

Canadian Cardiovascular Society Guidelines on Perioperative Cardiac Risk Assessment and Management for Patients Who Undergo Noncardiac Surgery - PubMed (nih.gov)

Derivation and Prospective Validation of a Simple Index for Prediction of Cardiac Risk of Major Noncardiac Surgery | Circulation (ahajournals.org)

Revised Cardiac Risk Index for Pre-Operative Risk - MDCalc

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