Revised cardiac risk index
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Revised Cardiac Risk Index (RCRI) Overview and Key Risk Factors
The Revised Cardiac Risk Index (RCRI) is a widely used tool for predicting the risk of major cardiac complications in patients undergoing non-cardiac surgery. The original RCRI includes six risk factors: high-risk type of surgery, history of ischemic heart disease, history of congestive heart failure, history of cerebrovascular disease, preoperative treatment with insulin, and preoperative serum creatinine >2.0 mg/dL. The risk of major cardiac complications increases with the number of these risk factors present, with event rates ranging from about 0.5% for patients with no risk factors to 9-11% for those with three or more risk factors 78.
Predictive Performance and Limitations of the RCRI
The RCRI has shown moderate ability to distinguish between low- and high-risk patients for cardiac events after mixed non-cardiac surgery, with area under the receiver operating characteristic curve (AUC) values typically around 0.73 to 0.79 1468. However, its predictive accuracy is lower for vascular surgery and for predicting overall mortality, with AUC values dropping to around 0.62 to 0.64 in these settings 46. The RCRI also performs less well in certain populations, such as older Chinese patients with known coronary artery disease, where it was found to be no better than chance (AUC = 0.53) .
Modifications and Recalibrations of the RCRI
Recent studies suggest that modifications to the RCRI can improve its predictive value. For example, replacing serum creatinine with a glomerular filtration rate (GFR) <30 mL/min as a risk factor resulted in better prediction of major cardiac complications, maintaining the same AUC but improving risk stratification . In lung resection candidates, a recalibrated RCRI that focused on cerebrovascular disease, cardiac ischemia, renal disease, and pneumonectomy provided better discrimination than the traditional RCRI (c index 0.72 vs. 0.62) . Additionally, a modified RCRI (mRCRI) has been shown to predict not only cardiac but also non-cardiac postoperative morbidity and prolonged hospital stay after elective orthopedic surgery .
RCRI and Long-Term Outcomes
The RCRI is also associated with longer-term outcomes. Higher RCRI classes are linked to increased 1-year postoperative mortality, regardless of patient sex, age, or type of anesthesia. Patients in the highest RCRI class had more than double the risk of 1-year mortality compared to those in the lowest class .
Calls for a New or Improved Cardiac Risk Index
Given the limitations of the RCRI, especially in specific patient groups and surgical types, there is a recognized need for a new or improved cardiac risk prediction model. Suggestions for improvement include incorporating additional GFR cut points, age, history of peripheral vascular disease, functional capacity, and specific surgical procedural categories to enhance discrimination and global applicability .
Conclusion
The Revised Cardiac Risk Index remains a useful and simple tool for preoperative cardiac risk assessment in non-cardiac surgery, with moderate predictive accuracy in general populations. However, its limitations in certain subgroups and surgical specialties have prompted efforts to recalibrate or modify the index for better performance. Ongoing research aims to develop more accurate and universally applicable risk prediction models for perioperative cardiac events.
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