1.1 Research Objects
This retrospective study included 1037 patients with acute myocardial infarction were hospitalized and received PCI treatment in the Department of Cardiology of Shanghai General Hospital and Jiading Branch of Shanghai General Hospital from January 2016 to May 2021, including 573 males and 464 females, aged (64.84±13.68) years. All enrolled patients were divided into two groups according to TIMI blood grade after PCI. Among them, 309 patients in no-reflow group, including 181 males and 128 females, aged (65.76±12.68) years; 728 patients in reflow group, including 406 males and 322 females, aged (62.89±13.54) years.
① Patients with congenital heart disease, valvular heart disease, rheumatic heart disease, cardiomyopathy and pulmonary heart disease; ② Patients who had undergone PCI or coronary artery bypass grafting, had the history of old myocardial infarction or decompensated heart failure; ③ Patients with confirmed familial hypertriglyceridemia; (4) Patients who had taken statins and triglyceride lowering drugs before admission; (5) Severe liver and kidney insufficiency（Transaminase is greater than or equal to 2 times the normal value；GFR＜60ml/(min*1.73m2）; ⑥ Patients with autoimmune diseases, significant infections, thyroid and adrenal dysfunction, blood diseases, malignant diseases, and a history of surgical trauma 3 months before admission. ⑦ Patients with fasting glucose level higher than 6.9 mmol/L or taking hypoglycemic drugs.All study protocols of participants were reviewed and approved by The Medical Ethics Committe of JiaDing branch of Shanghai General hospital and followed the recommendations of Declaration of Helsinki.
1.2 Diagnostic criteria and definition
Acute myocardial infarction: Chest pain with new ST-segment changes and elevated markers of myocardial necrosis to at least twice the upper normal value. TIMI blood grade criteria: Grade 0: No forward blood flow through infarct-related vessels; Grade 1: The contrast agent partially passes through the diseased vessels, and the distal vascular bed cannot be completely filled by the contrast agent; Level 2: contrast agent can fill the entire vascular bed, but the filling and emptyspeed is very slow, more than 3 cardiac cycles; Level 3: The contrast agent rapidly fills the distal vascular bed and empties it rapidly over 3 cardiac cycles. No reflow: postoperative TIMI blood flow ≤2(Figure 1).Reflow was defined as TIMI flow 3.(Figure 2)
1.3 Research Methods:
1.3.1 General data: General clinical data such as gender, age, height, weight, hypertension and smoking history of the patients were collected through the electronic medical record system.
1.3.2 Laboratory data: after admission, 3ml fasting elbow venous blood was collected from all patients and placed in anticoagulant tubes for examination. Roche Cobas8000 automatic biochemical analyzer was used to detect the blood biochemical indexes of patients, and SYSMEX XN-9000 automatic blood cell analyzer was used to detect and analyze myocardial injury markers, blood routine and other items. TyG index =Ln[serum triglyceride (mg/ dl) ×fasting glucose (mg/dl) /2]. All patients received oral aspirin 300mg, ticagrelor 180mg, and low molecular weight heparin 4100IU intravenously before surgery. Innova 3100 fully digital angiography machine was used, with iodipin as contrast agent. PCI operation and TIMI blood grade diagnosis were performed by 2 or more experienced senior physicians with intervention qualification.
1.3.3 Echocardiography and myocardial contrast echocardiography;
All patients underwent cardiac ultrasound and myocardial contrast echocardiography in the department of cardiology of the hospital on the 5th day after admission. The patient was placed in left decubitus position and underwent conventional ultrasound section, left ventricular long axis four-chamber view, three-chamber view and two-chamber view respectively for cardiac ultrasound examination. After routine cardiac ultrasound examination was completed, myocardial contrast echocardiography was performed. Shanghai Bolai sulfur six fluoride microbubble powder injection was used as contrast agent. High mechanical index (MI=0.57) was used to release high energy pulses to destroy microbubbles, and then low mechanical index (MI=0.07) was used for contrast examination to observe the filling of contrast agent in each cardiac muscle segment. The following indexes were measured and recorded: left ventricular diastolic diameter (LVIDd), left ventricular end-systolic volume (LVESV), mitral e-peak velocity (MVE), mitral a-peak velocity (MVA), left ventricular mass index (LVMASSI), left ventricular ejection fraction (LVEF), and ventricular wall motion index (WMSI). WMSI was calculated as follows: According to the regulations of American Association of Cardiac Ultrasound, the left ventricular long axis four-chamber, three-chamber and two-chamber sections were divided into 16 segments. Myocardium of each segment was scored according to ventricular wall motion. Scoring criteria: 1 point: normal ventricular wall motion; 2 minutes: the motion of the chamber wall was weakened; 3. The wall motion disappeared; 4 points: contradictory movement of chamber wall; WMSI= sum of scores of each segment/number of summary segments. After contrast, score was given according to the filling degree of each myocardial contrast agent: 1: uniform and obvious perfusion of myocardial tissue; 2 points: mild uneven perfusion of myocardial tissue; 3 points: myocardial tissue perfusion defect; Contrast agent score index (CSI)= sum of fractions of each segment/total segment number.
1.4 Statistical treatment
SPSS 26.0 data software was used for statistical analysis. All measurement data were first tested for normality, and the data conforming to normal distribution was expressed as (x±s). The comparison between the two groups was performed by T test. Data that did not conform to the normal distribution was represented by M(P25, P75), and non-parametric test was used for comparison between the two groups. Enumeration data were presented as an example (%), and rank sum test was used for comparison between the two groups. Pearson or Spearman correlation analysis was selected according to whether the data type conforms to the normal distribution. Logistic regression analysis was used for multivariate analysis. ROC curve was used to calculate the prediction cut-off point of TyG index with the highest specificity and sensitivity. Bilateral test was adopted, and the test level was P<0.05.