Radiation delivered via intracoronary brachytherapy is feasible for treating recurrent drug-eluting stent (DES) restenosis, according to a single-center registry study.
There were no procedural adverse events in 99% of brachytherapy sessions targeting the site of in-stent restenosis, nor were there any subacute cases of thrombosis, Ron Waksman, MD, of MedStar Washington Hospital Center/Georgetown University, and colleagues reported online in JACC: Cardiovascular Interventions.
However, the intervention appeared to be a short-term fix in many cases. “Over time, there is a gradual attrition in patency requiring repeat intervention,” the authors acknowledged.
Target lesion revascularization occurred in 3.3% of patients at 6 months, 12.1% at 1 year, 19.1% at 2 years, and 20.7% at 3 years. Target vessel revascularization rose from 7.1% at 6 months to 30.5% at 3 years.
“A major pre-disposing factor for the first episode of DES in-stent restenosis is stent under-expansion, while that for recurrent DES in-stent restenosis is exaggerated intimal hyperplasia response,” according to Waksman’s group. As such, ionizing radiation cuts off the cell cycle inherent in that response.
David O. Williams, MD, and Piotr S. Sobieszczyk, MD, both of Boston’s Brigham and Women’s Hospital, agreed that the results were “not perfect.”
Yet brachytherapy — a treatment for bare metal stent restenosis that has been eclipsed in the contemporary era of DES — “should not disappear,” the duo argued in an accompanying editorial. “Although there are fewer patients who may need brachytherapy for DES in-stent restenosis, they will always exist. Given the findings from this study, this treatment can be highly effective. Physicians should be aware of the value of brachytherapy and be prepared to offer it to patients in need.”
With coronary drug-coated balloons unavailable in the U.S., the growing interest in brachytherapy has been reflected in the rising number of catheterization labs that offer the therapy, according to Waksman and colleagues.
Even so, intravascular brachytherapy is still uncommon, as this treatment is only rarely offered at hospitals in the U.S. and largely absent from U.S. guidelines, noted Williams and Sobieszczyk.
A major challenge for brachytherapy is the required “presence of a radiation oncologist and at times a radiation physicist in addition to an interventional cardiologist,” the editorialists noted. “Assembling this team in one place and at one time may be difficult.”
Waksman’s study included 186 patients with failed first- and second-generation DES. The majority of lesions had three or more prior episodes of target lesion revascularization (95%).
Before receiving radiation, most lesions were treated with balloon angioplasty; whereas repeat stenting was rare (2% of patients got a DES and 4% a bare metal stent).
Death was observed in 3.8% of cases at 6 months, reaching 13.2% by year 3. The rates of myocardial infarction were 0.5% and 6.7%, respectively.
Only one patient exhibited late thrombosis at a third-year check-up (<1%). “This could partially be due to the use of more effective pharmacotherapies in percutaneous coronary intervention in the current era. Late thrombosis events are related to delayed re-endothelialization after intravascular brachytherapy and can be prevented by prolonged antiplatelet therapy,” the authors suggested.
The investigators called the short- and medium-term outcomes “reasonable” considering the complex patients treated.
Ultimately, they concluded that this type of radiation therapy is “particularly attractive in patients with recurrent DES in-stent restenosis and those with complex lesions where re-DES may be extremely challenging and unlikely to be procedurally successful.” Among the advantages of radiation over re-stenting are “less inflammation, no additional layers of polymers, and no further encroachment on an already narrowed lumen.”
Waksman and colleagues nonetheless acknowledged that the study “suffers from [the] limitations of a retrospective design” and the lack of a control group receiving balloon angioplasty alone.
Furthermore, there were no follow-up angiography data. “Thus, we do not know the real restenosis rate following brachytherapy,” cautioned Williams and Sobieszczyk.
Waksman reported consulting for Abbott Vascular, Biotronik, Boston Scientific, Medtronic, and St. Jude Medical; as well as serving on the speakers bureaus of AstraZeneca, Boston Scientific, and Merck; and receiving research grant support from AstraZeneca, Biotronik, and Boston Scientific.
Williams and Sobieszczyk declared no conflicting interests.
JACC: Cardiovascular Interventions
Negi SI, et al “Intracoronary brachytherapy for recurrent drug-eluting stent failure” JACC Cardiovasc Interv 2016; DOI: 10.1016/j.jcin.2016.03.018.
JACC: Cardiovascular Interventions
Williams DO, et al “Coronary brachytherapy 2016” JACC Cardiovasc Interv 2016; DOI: 10.1016/j.jcin.2016.04.033.