Risk factors of in-stent restenosis among coronary artery disease patients with syphilis undergoing percutaneous coronary intervention: a retrospective study

Background The risk factors of in-stent restenosis (ISR) among coronary artery disease (CAD) patients with syphilis after percutaneous coronary intervention (PCI) are not fully understood. Therefore, this study aimed to elucidate not only the risk factors of ISR among CAD patients with syphilis after performing PCI, but also the population attributable risk percentage (PAR%), which is used to quantify the proportion of ISR that could be eliminated if particular risk factors are not present. Methods Evaluation of the prevalence, risk factors, and their PAR% for ISR among CAD patients with syphilis undergoing PCI was conducted retrospectively at Beijing Ditan Hospital. CAD patients with syphilis underwent PCI from August 2010 to August 2019 and received a diagnosis, coronary angiography, PCI, and periodical follow-up. The clinical, laboratory, and imaging data were reviewed and summarised anonymously from electronic medical records. The chi-square or Fisher exact test was used in data analysis. Results Among 114 CAD patients with syphilis undergoing PCI, ISR occurred in 18 patients (15.78%). The multivariate Cox regression model indicated that average stent length ≥ 35 mm (adjusted hazard ratio [HR] = 4.47, 95% confidence interval [CI] = 1.30–15.44, p = 0.018) and titres of the toluidine red unheated serum test (TRUST) > 1:16 (adjusted HR = 3.72, 95% CI = 1.22–11.36, p = 0.021) were associated with an increased risk of ISR, while successful antisyphilitic treatment (adjusted HR = 0.12, 95% CI = 0.02–0.95, p = 0.045) was protective predictor of ISR among these patients. The PAR% values of particular risk factors associated with ISR including average stent length ≥ 35 mm, titres of TRUST > 1:16, and successful antisyphilitic treatment were 12.2%, 24.0%, and -39.6%, respectively, among these patients. Conclusions Preventing the occurrence of ISR among CAD patients with syphilis undergoing PCI requires clinical intervention. Our results indicated that carefully evaluating the length of the vessel lesion to determine whether the stent length is < 35 mm, prioritising the clinical intervention for titres of TRUST > 1:16, and providing successful antisyphilitic treatment could reduce the risk of ISR occurrence.