Intracoronary Brachytherapy in the Era of Drug-Eluting Stents

Abstract

Intracoronary brachytherapy (ICBT) is an effective percutaneous trans-luminal solution for in-stent restenosis (ISR). Our objective is to assess the feasibility, safety, and efficacy of ICBT as a treatment option for ISR. We retrospectively identified adult patients who underwent ICBT for ISR in our institution, between March 2015 and January 2017 in an IRB approved database. All lesions were treated with Y-90 source, with an activity of 1.66 gigabecquerel to a prescription depth of 2mm. Lesions were prescribed 18.4 Gy (n=35), for reference vessel diameter (RVD) of < 3.35 mm or 23 Gy (n=36) for RVD of ≥ 3.35mm. Demographic variables, rates of peri-procedural complications and incidence of target lesion revascularization (TLR) were collected. Predictors of TLR were determined using Cox proportional hazards modelling. We identified 60 patients treated to a total of 71 lesions with 11 patients undergoing a second ICBT procedure. The median age of patients was 66 years with a median follow-up of 5 months. All patients had hyperlipidemia, 63% were male, 98.3% were hypertensive, and 58.3% had diabetes. Never smokers, former smokers, and current smokers represented 49.3%, 39.4%, and 11.3% respectively. The number of previous ISR at the site of ICBT was known for 47 treatments with < 4 prior ISR in 56.8% and ≥4 in 43.2%. Number of stent layers at the site of ICBT was known for 58 lesions and was < 2 layers in 65.5% and ≥3 in 34.5%. Left anterior descending artery (LAD) was the most commonly treated vessel (32.4% of ICBT). The median true vessel diameter (TVD) was 3.4 mm (range, 2.5-4.5), median injury length was 32 mm (range, 5-120mm) and median number of dwell positions was 1 (range, 1-4). Fifteen lesions (21.1%) required TLR resulting in 6 and 12-month actuarial rates of ISR of 9% and 30.3% respectively. No peri-procedural myocardial infarctions, arrhythmias, vessel perforations or dissections were observed. Univariate analysis revealed an association between TLR and history of prior ICBT HR = 3.24 (95% CI 0.93 - 12.7 p = 0.065), fewer stent layers HR = 3.13 (95% CI 0.70 – 14.0 p = 0.14) and a higher number of previous ISR at the ICBT site HR = 2.25 (95% CI 0.71 to 7.14 p = 0.17). There was no statistically significant association between TLR and age (p = 0.36), sex (p = 0.57), DM (p = 0.46), smoking (p = 0.97), TVD (p = 0.76), radiation dose (p = 0.77) or number of dwell positions (p = 0.71). One patient has died resulting in an actuarial overall survival rate of 83.3% at 24 months. ICBT in the era of drug-eluting stents is a feasible and safe treatment option for patients with ISR with low rates of severe peri-procedural complications. This preliminary report suggests a history of prior ICBT may be associated with a higher rate of TLR after ICBT. For patients with in-stent restenosis in the era of drug-eluting stents, ICBT should be considered to minimize the risk of ISR.