Objective To evaluate the predictive abilities of the triglyceride and glucose(TyG)index,metabolic insulin resistance score(METSIR),and ratio of triglyceride to high-density lipopro-tein cholesterol(TG/HDL-C)for the risk of onset and severity of lesions in patients with acute coro-nary syndrome(ACS)complicated with multivessel coronary artery disease.Methods A retrospec-tive analysis was conducted on the clinical data of 260 ACS patients admitted to Yunnan Provincial Third People's Hospital,and the patients were divided into multivessel disease group(n=160)and non-multivessel disease group(n=100);based on the SYNTAX score,the multivessel disease group was further divided into high-risk group with 71 cases(score＞22.5)and low-risk group with 89 cases(score ≤22.5).Results The multivessel disease group had significantly higher proportions of males,history of diabetes,history of smoking,TyG index,METSIR,and TG/HDL-C compared to the non-multivessel disease group(P＜0.05).Correlation analysis showed that the TyG index and TG/HDL-C were significantly positively correlated with the SYNTAX score(P＜0.05),while MET-SIR had no correlation with the SYNTAX score(P＞0.05).Logistic regression analysis indicated that METSIR was an independent risk factor for ACS complicated with multivessel coronary artery disease(P＜0.05),and TyG,METSIR and TG/HDL-C were all independent factors for predicting the severity of lesions(P＜0.05).Receiver operating characteristic(ROC)curve analysis showed that TyG had the highest predictive value for ACS complicated with multivessel coronary artery dis-ease and its severity(area under the curve was 0.804).Conclusion The TyG index,METSIR,and TG/HDL-C are of great significance in the early identification and assessment of ACS complicat-ed with multi vessel coronary artery disease,with TyG having the highest predictive value.