761-3 Interventlonal Treatment of “Insignificant” Stenoses

Traditionally, coronary lesions with<50% diameter stenosis are considered clinically insignificant. However, these lesions often initiate acute coronary thrombosis and infarction. Moreover, they are regularly if unintentional treated when interventionalists “clean up” a diffusely diseased vessel. To investigate this issue, quantitative analysis was applied to 3,799 discrete stenosis undergoing PTCA at multiple centers. Of these, 668 (17.9%) possessed a pre-procedural diameter stenosis of<50%. These lesions were further subgrouped by terciles (≤42%, 42-47%,>47%). Compared to diameter stenoses≥50%, these lesions were significantly more eccentric (p<0.0001 l, shorter (p <0.0001 l) located in the LAD (p=0.0003), and associated with multilesion PTCA (p<0.0001). The therapeutic approach chosen involved larger balloons (balloon/artery ratio=1.21 vs 1.10, P<0.0001) but was accompanied by shorter inflation times (264 sec vs 320 sec, p<0.0001). Although the acute improvement in MLD was less (0.39 vs 0.81 mm, p<0.0001) loss of this improvement during follow-up was relatively high (loss index=0.86 vs 0.44, P=0.013), so that the net improvement at 6 months was one third that seen with the more severe stenoses (net gain=0.17 vs 0.48 mm, p<0.0001). Moreover, a substantial proportion of stenoses were more severely narrowed 6 months after the procedure than before (29.0% VS 15.4%, P<0.0001). Conclusion Treatment of “insignificant” stenoses is relativelyfrequent. Despite more aggressive balloon sizing, short and intermediate term results are disappointing.