Intracoronary brachytherapy not associated with changes in major side branches

Intravascular radiation (IR) is emerging as a potential solution for the pr evention and treatment of restenosis. Subacute thrombosis late coronary occ lusion of the target lesion after intracoronary brachytherapy has been desc ribed in two studies. None of these studies assessed in detail the evolutio n of side branches following IR. The purpose of this study was to determine the frequency of side-branch occlusion in patients undergoing IR. We evalu ated the procedural and 6-month follow-up angiograms of 170 consecutive pat ients enrolled in the GAMMA-I and WRIST studies who presented a major side branch (diameter > 1.5 mm) at the treated lesion. Major side branches treat ed during the procedure and/or total occlusion of the main branch were excl uded for analysis. Sixty-three patients (control = 30, irradiated = 33) wer e identified and side branches were classified in one of three categories: no significant stenosis, > 50% stenosis, and occluded. The baseline patient and lesion characteristics were similar among the classified groups. No di fference was observed between the control and irradiated arteries after the procedure for side-branch occlusion (14% and 9%, P = NS). A significant de crease of restenosis was observed after IR compared to control (20% vs. 70% : P < 0.001). The patency rates and rates of side-branch occlusion were sim ilar between the two groups. However, in the control group, 50% of the side -branch occlusions that occurred after the procedure were patent at 6-month follow-up. In contrast, in the irradiated group, the incidence of side-bra nch occlusion increased from 9% to 15% at 6-month follow-up in the irradiat ed group. Low doses of radiation applied to noninjured side branches are no t associated with adverse effects. The absence of restoration patency follo wed by IR is most likely a consequence of a delayed healing process. Cathet . Cardiovasc. Intervent 51:154-158, 2000. (C) 2000 Wiley-Liss, Inc.