Modification of endothermal heat-induced thrombosis follow-up strategy using a risk stratification model after endovenous thermal ablation

Objective To develop and validate a risk stratification model that identifies varicose vein patients at high risk of Endothermal Heat-Induced Thrombosis (EHIT) following thermal ablation to guide optimized surveillance and anticoagulation strategies. Methods In this single-center retrospective cohort study, a total of 525 affected limbs treated by radiofrequency and microwave ablation were included. Patients were randomly assigned to a training cohort (n = 368) and a validation cohort (n = 157) in a 7:3 ratio. Preoperative clinical data, including Great saphenous vein (GSV) diameter, reflux time, sex, and Clinical Etiology Anatomy Pathophysiology (CEAP) classification, were analyzed. Predictors were identified through Spearman correlation and χ 2 tests. The model’s performance was assessed using C-index and confusion matrix in the validation cohort. All data analysis and visualization were performed using R software, with a p-value below 0.05 considered statistically significant. Results EHIT occurred in 24 patients (overall rate: 4.57%) at 1 week postoperatively. Of these, 21 were EHIT class I and 3 were EHIT class II. Significant predictors included GSV diameter, reflux time, CEAP classification and sex. The logistic regression model demonstrated strong calibration and discrimination (C-index = 0.853 in train cohort), with an optimal risk threshold of 5.4% established for risk stratification. In the validation cohort, the model achieved 79.61% accuracy, 100% sensitivity, and 78.8% specificity. A web-based calculator was developed to assist clinicians in estimating individual EHIT risk and guiding surveillance strategies. Conclusion We identified sex, GSV diameter, reflux time, and CEAP classification as predictors and developed a logistic model with a 5.4% risk threshold for EHIT stratification. For patients classified as average-risk, omission of routine ultrasound surveillance could be considered, whereas high-risk patients may benefit from intensified ultrasound surveillance and extended anticoagulation, but external multicenter validation is required before adoption in clinical practice.