Anti-restenotic effect of copper-62 liquid-filled balloon in porcine coronary arteries: Novel use of a short half-life positron emitter

Purpose: To determine the efficacy of the use of copper-62, a positron emit ter with a half-life of 9.7 minutes, as an intracoronary brachytherapy (IRB T) source in the prevention of neointima formation (NF) following overstret ch balloon injury (BI) in the porcine model. Methods and Materials: Sixteen swine were treated after BI to their left an terior descending (LAD), left circumflex (LCX), and/or right coronary arter y (RCA), Twelve of the injured arteries received placebo and 10 received 25 Gy, delivered to 0.5 mm from the surface of the treatment balloon filled w ith liquid Cu-62. Dosimetry was based on Monte Carlo calculations. Two week s after treatment, the animals were sacrificed, and the treated coronaries were perfusion-fixed and stained. Intimal area (IA) and medial fracture len gth (FL) were analyzed by computer-aided histomorphometry. Results: The (Zn-62/Cu-62) generator, together with a rapid concentration p rocess, was successful in delivering the short-lived Cu-62 at the high conc entration required for intravascular brachytherapy (IVBT), The fracture len gth in the two groups was similar (2.10 +/- 0.57; 2.02 +/- 0.77; g = NS). A rteries studied showed significant reduction in NF (IA: 0.23 +/- 0.47 mm(2) vs. 1.08 +/- 0.57 mm(2); p < 0.01. IA/FL = 0.09 +/- 0.17 mm vs. 0.51 +/- 0 .21 mm; p < 0.01). Conclusions: This study demonstrated that use of liquid Cu-62 as an IVBT so urce is safe and feasible. All 16 swine tolerated the treatment well with n o radiation-induced side effects or symptoms throughout the 2-week period, The isotope delivered the dose necessary to inhibit NF in the porcine coron ary BI model. (C) 2000 Elsevier Science Inc.