Intravascular brachytherapy was safe and feasible as a short-term treatment for patients with recurrent drug-eluting stent (DES) in-stent restenosis, according to a new study published in JACC: Cardiovascular Interventions.
As study researchers explained, DES have a reduced rate of in-stent restenosis compared with bare-metal stents (BMS), but there is still a significant hazard of restenosis with the first year of percutaneous coronary intervention (PCI) and every year following.
Intracoronary vascular brachytherapy works by inhibiting cell proliferation via cell cycle inhibition. It has been approved for treatment of BMS in-stent restenosis, but has also been used to treat DES in-stent restenosis. Due to logistical issues, the therapy is only available in a few centers in the United States, which means that data on efficacy and safety are limited. Researchers sought to close those gaps in knowledge with this study.
Patients were selected from an ongoing clinical PCI registry at the authors’ institution, Georgetown University in Washington, DC. A total of 186 (283 lesions; average age: 65 ± 11 years) were included. There was a high prevalence of hypertension, diabetes, hyperlipidemia, chronic smoking, and chronic kidney disease, and more than half (55%) of patients had a history of prior coronary bypass surgery.
The primary end point was clinically-driven target lesion revascularization (TLR) at 30 days and at 1, 2, and 3 years of follow-up.
Mean time to failure from last failed DES implantation was 450.65 ± 50 days, and a majority of patients had more than 2 episodes of TLR. Unstable angina was the most common clinical presentation of DES in-stent restenosis, with few patients (n=7) presenting with ST-segment elevation myocardial infarction (MI).
In approximately 68% of the total lesions, the failed stent was a first-generation DES with a mean length of 21. 61 ± 6.7 mm and mean diameter of 3.08 ± 1.7 mm. Lesions were treated with balloon angioplasty followed by intravascular brachytherapy using the Beta-Cath system (Best Vascular Inc.). At 6 months, incidence of TLR was 3.3%, 12.1% at 1 year, 19.1% at 2 years, and 20.7% at 3 years.
At 30 days, TLR-major adverse cardiovascular event (MACE) incidence was 1.1% and the target vessel revascularization (TVR) MACE was 2.2%. At 6 months, TVR-MACE increased to 9.7% while TLR-MACE increased to 6.5%. This upward trend of both TLR and TVR-MACE persisted at follow-up for 1, 2, and 3 years (16.8% and 23%, 27.6% and 39.2%, and 31.9% and 44.1%, respectively). Incidence of MI was 6.7% and all-cause mortality was 13.2%. Rate of late stent thrombosis was low at 1, 2, and 3 years (0.5%).
“In these patients, there are clear advantages to using VBT [intravascular brachytherapy] over another DES, as repeat stenting carries the risk of stent thrombosis and re-ISR,” researchers wrote. “In addition, VBT is associated with less inflammation, no additional layers of polymers, and no further encroachment on an already narrowed lumen.”
While the overall recurrence rate for DES in-stent restenosis may be as high as 12% at the 1-year mark, that rate, researchers stated, may be acceptable in these complex patients who have had multiple stent failures.
They concluded by urging further studies to examine specific patient population, who are usually excluded from large trials, to better assess head-to-head treatment strategies for DES in-stent restenosis.
Negi SI, Torguson R, Gai J, et al. Intracoronary brachytherapy for recurrent drug-eluting stent failure. JACC Cardiovasc Interv. 2016;9(12):1259-1265. doi: 10.1016/j.jcin.2016.03.018.