A Five-Parameter Score for Predicting Saphenous Vein Graft Degenerative and/or Occlusive Disease in Recurring Ischemic Symptoms After Coronary Artery Bypass Grafting

Abstract

Background: The recurrence rate of ischemic symptoms after coronary artery bypass grafting (CABG) is increasing in recent years. How to prevent and treat saphenous vein graft disease (SVGD) has been a clinical challenge to date. Although studies on risk factors for SVGD have been published, there is currently no available score for estimating the risk of SVGD. We sought to develop and validate a scoring system to predict SVGD among patients who recurring ischemia post CABG. Objective: To inform research on patient management including modifiable risk factors for SVGD [symptomatic ≥ 50% stenosis in at least 1 Saphenous vein grafts (SVG)], we sought to develop and validate a simple predictive clinical risk score index for SVGD with recurring ischemia after CABG. Methods and Results: This was a retrospective cohort study and the results were validated using bootstrap resampling on a separate cohort. A nomogram and risk scoring system were developed based on retrospectively collected data from a training cohort of 606 consecutive patients who were readmitted at Tianjin Chest Hospital between March 2015 and December 2017 with recurring ischemia >1 year after CABG. Logistic regression model was used to find the predictive factors and to build a nomogram. The predictive accuracy and discriminative ability of the model for SVGD were determined by concordance (C) index and calibration curve. To assess the generalization, models were validated using bootstrap resampling and an external cohort of 187 consecutive patients enrolled between March 2017 and December 2018 at 4 other local hospitals. In multivariable analysis of the primary cohort, native lesion vessel number, SVG age, recurring ischemia type, very low-density lipoprotein level, and left ventricular end-diastolic diameter were independent predictors of SVGD after CABG. A summary risk score was derived from nomogram, ranging from 0 to 30, with a cutoff value of 15. In internal and external validation, the C-index was 0.82[95%CI, 0.78-0.86] and 0.86 [0.79-0.92] for risk score-based predictions, indicating good overall discrimination. The calibration curve for probability of SVGD showed optimal agreement between actual observations and risk score prediction. Conclusions: A simple-to-use risk scoring system based on five easily obtainable demographic, clinical, biochemical variables was developed and validated to predict the risk of SVGD among patients who recurring ischemia post CABG. This score may be useful for providing patients with individualized estimates of SVGD risk. Funding Statement: This research project was funded by the Key Project of Scientific and Technological Support Plan of Tianjin in 2016 (No.16YFZCSY00800), the Key Project of Healthcare Industry of Tianjin in 2015 (No. 15KG128) and Major Science and Technology Projects of Tianjin Science and Technology Commission in 2016 (No. 16ZXMJSY00150). Declaration of Interests: All authors have no conflicts of interest to declare. Ethics Approval Statement: Ethical approval was obtained from participating institutions through their respective institutional review boards, and all participants provided written informed consent prior to treatment.