MSS04 Presentation Time: 4:00 PM: Clinical Outcomes of Intravascular Brachytherapy Used to Manage Coronary Artery In-Stent Restenosis with or without Excimer Laser Atherectomy

Abstract

<h3>Purpose</h3> Despite advances in percutaneous coronary intervention (PCI) for coronary artery disease, in-stent restenosis (ISR) necessitating recurrent revascularization continues to be problematic, leading to major adverse cardiovascular events (MACE) if left untreated.A 2015 meta-analysis of PCI modalities available to treat ISR reported on literature comparing ≥2 treatments for relative efficacy and safety. Two such treatments are intravascular brachytherapy and excimer laser atherectomy, with previous studies composed of RCTs with head-to-head comparisons rather than sequential use of these modalities.To date, an analysis comparing outcomes of intravascular brachytherapy alone (IVB-0) versus laser atherectomy directly followed by intravascular brachytherapy (IVB-A) has not been conducted. This study aims to address this gap by determining clinical outcomes in propensity matched cohorts of patients receiving IVB-0 versus IVB-A. <h3>Materials and Methods</h3> Data for this study were gathered via a chart review of patients previously treated at Houston Methodist Hospital's Cardiac Catheterization Laboratory from 2015 to 2020. Data acquired were subsequently used for propensity matching. Relevant patient information such age, sex, medical co-morbidities, overall major adverse cardiac events (MACE), target lesion revascularization, myocardial infarctions and death were reviewed and recorded.Patient characteristics were reported as frequencies and proportions for categorical variables and as median and interquartile range (IQR) for continuous variables. Differences across groups were determined by Chi-square or Fisher's exact tests for categorical variables and the Kruskal Wallis test for continuous variables as appropriate. Differences between groups was compared by the log-rank test. Sub-analysis was conducted in a propensity score matched cohort between intravascular brachytherapy alone (IVB-0) and IVB-A using the following matching criteria: Age, gender, body mass index, diabetes, smoker, hypertension, chronic kidney disease (on dialysis), and number of stent layers. All the analyses were performed on Stata version 16.1 (StataCorp LLC, College Station, TX, USA). A p value of <0.05 was considered statistically significant.Brachytherapy was delivered using a beta-particle producing 90Sr isotope in a triple lumen closed end catheter. A 40 mm in length source was placed in the vessel such that 5-10 mm of coverage was available on each end of the lesion. Radiation dosage was either 18.4 or 23 Gy, with vessels < 3.5 mm in diameter receiving 18.4 Gy and ≥3.5 mm receiving 23 Gy. The dwell time was calculated based on the length of the lesion. <h3>Results</h3> Graphic. <h3>Conclusions</h3> In all clinical outcomes considered, treatment with intravascular brachytherapy alone is not statistically significantly different to the addition of laser atherectomy to intravascular brachytherapy. With continuous improvements in the technologies used to treat of in-stent restenosis, it is of critical importance to consider clinical outcomes that may influence the standard of care. Based on our institutional experience, there are no clinically significant differences in the two technologies considered (IVB-0 and IVB-A). We suspect that as these modalities have previously been demonstrated to be highly effective in treating in-stent restenosis, a larger treatment population may be necessary to detect a significant difference in clinical outcomes. Importantly, additional work is necessary to compare intravascular therapy to target vessel or lesion revascularization with additional or multi-layer stents; this work is forthcoming.