A nomogramic model for predicting the left ventricular ejection fraction of STEMI patients after thrombolysis-transfer PCI

Figures

• 

  Figure 1. Flow chart of the study population selection. A total of 305 patients diagnosed with STEMI in primary hospitals and treated with pharmacological thrombolysis and reperfusion strategy were included in this study. However, 17 patients were excluded because of age >80 years, death in transportion, rejected PCI, or missing data, leaving 288 patients who were divided into two groups according to LVEF measured by echocardiography within 1 week after TTPCI.

• 

  Figure 2. (A) Screening plot of 26 variables by all-subsets regression, HR, heart rate; SBP, systolic blood pressure; TR, thrombolytic recanalization; WBC, white blood cell; PLT, platelet; dBil, direct bilirubin; Alb, albumin; ALT, alanine aminotransferase; LDL.C, low-density lipoprotein cholesterin; APTT, activated partial thromboplastin time; TT, thrombin time; BNP, brain natriuretic peptide; MYO, myohemoglobin; LAD, left anterior descending; LCA, left circumflex artery; LMC, left main coronary. (B) Regression coefficient of independent risk factors and forest plots. A total of six independent variables were obtained through both univariate and multivariate logistic regression. OR, odds ratios; 95% CI, 95% confidence interval.

• 

  Figure 3. A nomogram for predicting the LVEF ≥ 50% probability of STEMI patients with PCI. Age, years; HR, heart rate, rate/min; Hypertension; Smoking history; ALT, alanine aminotransferase, U/L; Killip class. Instructions for using the nomogram: (1) Draw a vertical line based on the value of each variable to obtain the corresponding point; (2) Add all six points to obtain the total point; (3) Draw a vertical line based on the total point to determine the estimated the LVEF ≥ 50% probability one week after TTPCI.

• 

  Figure 4. (A) The receiver operating characteristic (ROC) curve (a) and calibration curve (b) for the established nomogram. OR, odds ratios; AUC, area under the curve; 95% CI, 95% confidence interval. Calibration curve reflects the extent to which the model correctly estimates the absolute probability or agreement between the predicted probability and observed outcomes. (B) The y-axis represents the actual LVEF ≥ 50% probability. The x-axis represents the predicted LVEF ≥ 50% probability. The black dot at the top represents the prediction probability corresponding to the actual observation, the black dotted line represents the ideal predicted value, and the solid line represents the actual predicted value.

• 

  Figure 5. Determination of decision point via decision curve analysis (DCA) and clinical impact curve. (1) Decision curve for the prediction model. The decision curve analysis graphically shows the clinical usefulness of the nomogram based on a continuum of potential thresholds for LVEF ≥ 50% probability falling (x-axis) and the net benefit of using the nomogram to stratify patients (y-axis). Net benefit curves are plotted across probability thresholds for 6 options: “all” assume all patients have LVEF < 50%, “none” assume no patients have LVEF < 50%. Net benefit = (true positives/N)-(false positives/N) × (weighting factor). Weighting factor = threshold probability/(1-threshold probability). (2) Clinical impact curve for nomogram. The red line shows the total number who would be deemed as high risk of LVEF < 50% for each risk thresh.