Increased dosage during intracoronary irradiation due to overlapped source stepping shows no long-term adverse changes in vessel morphology.

Abstract

The purpose of this analysis was to evaluate if overdosage during intracoronary irradiation due to overlapped source stepping may result in long-term morphologic changes in vessel anatomy. Baseline angiograms of patients with in-stent restenosis undergoing coronary reintervention followed by intracoronary irradiation with source stepping were analyzed. Overlapping was considered present for the segment with overlapped reference isodose length (RIL) (RIL = segment with > or = 90% of reference dose at 1 mm vessel wall depth). Baseline and 6-months follow-up volumetric intravascular ultrasound (IVUS) analysis were performed for the overlapped segment and for proximal and distal segments of equal length. Overlapping was found in six patients (three patients: (32)P treatment; three patients: (90)Sr/Y treatment); final analysis was performed in four patients. Comparison of the baseline and follow-up IVUS volumetric parameters revealed no significant change in lumen or vessel volumes at segments of overlaps in comparison to proximal and distal reference segments. Increased dosage due to overlapping during source stepping is not associated with morphologic changes in vessel anatomy at follow-up.