Group-based trajectory modeling of hemoglobin change rate and impact of haemoglobin concentration on cardiovascular outcome after endovascular aneurysm repair a risk prediction model for persistent postoperative hemoglobin decline

Objective While postoperative hemoglobin decline following Endovascular Aneurysm Repair (EVAR) is a well-known phenomenon, the specific factors driving persistent hemoglobin reduction remain unclear. This observational, retrospective study seeks to establish distinct trajectories of hemoglobin change rates within the first 7 days following Endovascular Aneurysm Repair (EVAR) and to analyze the factors influencing persistent post-operative hemoglobin decline as well as Hb decrease, defined as preoperative minus postoperative Hb (g dl -1 ), on postoperative cardiovascular events in EVAR patients. Methods The study population consisted of all patients who underwent endovascular aneurysm repair (EVAR) for abdominal aortic aneurysm (AAA), totaling 1,995 individuals, between 1 June 2002, and 31 March 2024. Group-based trajectory modeling (GBTM) was utilized to categorize distinct patterns of hemoglobin changes over a 7-day period in patients following EVAR. Baseline clinical and demographic characteristics predictive of trajectory group membership were analyzed using univariate screening and two multivariate binary logistic regression. The development of the two risk prediction models for persistent postoperative hemoglobin decline in patients undergoing EVAR was undertaken using logistic regression. The corresponding nomograms were subsequently constructed. The study second endpoint was 30-day postoperative cardiovascular events, including. myocardial infarction, heart failure, arrhythmias, stroke, asymptomatic troponin-T release and cardiovascular death. Results We identified two trajectory groups: ' The decrease surpasses 20%' (n = 251, 16.8%) and ‘under 20%' (n = 1,528, 83.2%). After adjusting for potential confounders, these groups were significantly linked to clinical outcomes like age, PAD, aneurysm characteristics. Intraoperative factors such as operation duration, blood loss, and graft details also showed associations. A risk prediction model, visualized with a nomogram, included factors like age, PAD, a larger maximum AAA diameter, and Iliac artery aneurysm presenting with bilateral involvement, achieving an AUC of 0.733 (95% CI: 0.690–0.775). The model showed 70.0% sensitivity and 66.7% specificity, with a calibration chart confirming strong alignment between observed and predicted values, and a clinical decision curve highlighting its potential clinical utility. Conclusion In conclusion, our study identified that older age, maximum diameter of abdominal aortic aneurysm, and Iliac artery aneurysm presenting with bilateral were associated with continued hemoglobin decline post-EVAR. A drop in hemoglobin concentration exceeding 20% after elective EVAR surgery strongly predicts cardiovascular events within 30 days.