KEY POINTS
- This prospective registry analysis evaluated 26 coronary vessels in 19 patients with repeatedly recurrent in-stent restenosis. Each vessel served as its own control by comparing the restenosis-free interval before and after intravascular brachytherapy.
- Brachytherapy was delivered after percutaneous coronary intervention using a strontium-90 beta source. Prescribed doses were 18, 23, or 34 Gy at 2 mm from the source, using 40- or 60-mm source lengths and dwell times of approximately 5-10 minutes.
- The median restenosis-free interval increased from 96 days before brachytherapy to 350 days afterward, with a highly significant separation between the two intervals (p<0.001).
- Before brachytherapy, restenosis-free intervals ranged from 25 to 317 days. After treatment they ranged from 30 to 612 days, and only 5 vessels had developed another restenosis at the time of analysis.
- Importantly, post-treatment angiography was performed only when symptoms suggested recurrent stenosis rather than by routine surveillance. Any asymptomatic recurrence could therefore have been missed.
- The brachytherapy procedures also used somewhat more interventional devices than the preceding coronary interventions, averaging 3.2 versus 2.4 devices, creating a potential procedural confounder.
- The study was small, heterogeneous and non-randomized. It cannot establish superiority over alternatives such as drug-coated balloons, but it provides prospective within-patient evidence that intravascular radiation may meaningfully delay another recurrence.
CLINICAL TAKEAWAY
For patients with repeatedly recurrent coronary in-stent restenosis, intravascular brachytherapy substantially prolonged the interval before another clinically detected restenosis in this small cohort. The signal is compelling enough to support continued use in selected refractory cases, but comparative trials are still lacking.