Comparative study of cardiac risk indices to predict perioperative cardiovascular outcome in patients with peripheral vascular diseases

Introduction: Existing methodologies and risk stratification indices for predicting peri-operative cardiac complications in vascular surgery patient lack sufficient predictive value and therefore cannot be recommended for risk stratification. There are no Indian studies for preoperative cardiac risk scores for patients who undergo vascular and endovascular procedures. Therefore, an attempt was made to risk stratify and compare two existing cardiac risk indices (i.e., Detsky's modified cardiac risk index vs. Revised cardiac risk index [RCRI]) to predict peri-operative morbidity and mortality due to cardiac causes. The aim of this study: (a) To compare Detsky's modified cardiac risk index and RCRI to predict perioperative cardiovascular outcome in patients with peripheral vascular disease undergoing surgical intervention. (b) To predict perioperative cardiovascular outcome based on cardiac risk index in patients with peripheral vascular disease undergoing surgical intervention. Materials and Methods: This is an observational, prospective, longitudinal, controlled cohort study, which assessed 103 patients admitted at vascular centre for a period of 2 years. All patients undergoing vascular surgical procedure and evaluated by a cardiologist in the preoperative period were included in the study. Results: Eighteen patients (17.4%) had cardiac complications. The Detsky's index was found to be a satisfactory predictor of postoperative cardiac events (P < 0.001) as compared to RCRI which had a P < 0.003. There were a total of 10 mortalities (9.7%). Detsky's model and RCRI had positive predictive value (PPV) of 73.3% and 31.4%, specificity of 94.1% and 72.7%, respectively. Discussion: The overall sensitivity, specificity, PPV, negative predictive value of the Detsky's risk index, and RCRI in the prediction of cardiac events were 31.4%, 94.1%, 73.3%, 72.7% and 73.3%, 72.7%, 31.4%, 94.1%, respectively. In our study, the area under ROC for Detsky class was 0.76 versus 0.75 and superior to C statistic. However, the area under ROC for RCRI class was 0.72 versus 0.75 and inferior to C statistic. One important inference from the study was that 77.6% patients were smoker in the study group which emphasize the direct relation of peripheral vascular disease with smoking. Conclusion: The study concluded that patients with good surgical risk and profile undergoing minor vascular procedures can be operated without further testing. For other patients, the next step would be to incorporate the Detsky index. A Detsky score of 20 or more is comparable to a major clinical predictor in the American College of Cardiology/American Heart Association scheme.