Natural history of intravascular ultrasound-detected edge dissections from coronary stent deployment.

BACKGROUND: High-resolution intravascular ultrasound (IVUS) performed immediately after stent deployment often reveals dissection at the stent margin that may not be appreciated by angiography. However, the natural history of these edge dissections is unknown. These intimal disruptions at the stent margins have been previously reported to occur in 5% to 23% of stent implantations. The short-term prognosis of these lesions appears to be good; however, the longer-term effect on restenosis and/or vessel remodeling is not known. We therefore studied a cohort of patients with the use of IVUS immediately after stent implantation and at 6 months to assess the incidence and prognosis of coronary edge dissections. METHODS AND
RESULTS: One hundred fifty patients undergoing Palmaz-Shatz stent implantation were imaged with IVUS with the use of a motorized pullback, and the incidence of edge dissections was determined and graded according to depth and circumferential extent. Arterial and lesional morphometric parameters were assessed by digital planimetry. Six-month IVUS images were aligned with the poststent IVUS to determine the natural history of these lesions. Sixteen (10.7%) of 150 had edge tears. All were angiographically silent. Most lesions (n = 9) were superficial intimal tears. Vessel, lumen, and plaque area were similar in the nondissection and dissection groups in both the proximal and distal reference segments. Plaque eccentricity was likewise similar in both groups. At 6 months, lesions (n = 12) healed without a change in plaque burden, undergoing a "tacking down" process. Vessel area (19. 1 +/- 6.4 vs 18.4 +/- 7.1 mm(2), P = not significant), lumen area (8. 2 +/- 4.1 vs 9.2 +/- 4.0 mm(2), P = not significant), and plaque area (10.0 +/- 3.3 vs 9.8 +/- 3.3 mm(2), P = not significant) were unchanged when compared with the lesion site taken at stent deployment.
CONCLUSIONS: Edge dissections as detected by IVUS do not necessarily proscribe an adverse prognosis at 6 months. This finding may provide reassurance to interventionalists because these lesions are frequently seen by IVUS after stent deployment. Further studies are warranted to precisely define specific morphometric features of edge dissections that affect the long-term clinical outcome.