INTRACORONARY ULTRASOUND DURING RECANALIZ ATION OF CHRONIC CORONARY OCCLUSIONS - RELATION TO RESTENOSIS AND REOCCLUSION AFTER BALLOON ANGIOPLASTY OR STENT IMPLANTATION

Chronic coronary occlusions carry a high recurrence rate, and coronary stenting evolves as a preferred therapy of these complex lesions. Ins ight into the morphology of the occluded segment by intracoronary ultr asound may provide information which may help to improve the intervent ional strategy and the long-term outcome. After successful recanalizat ion of chronic coronary occlusions (4 weeks to 33 months; median 3.2 m onths) in 59 patients, 29 patients were treated by balloon angioplasty alone, and 30 patients received one or more coronary stents because o f complicated dissections or a high-grade residual stenosis after ball oon dilatation. Intracoronary ultrasound was used to assess the lesion morphology and to quantify the angioplasty result. The luminal area, the total vessel area and the extent of the plaque burden were measure d proximal and distal to the occlusion and at the narrowest site withi n the occlusion or the coronary stents, and the elastic recoil was cal culated. Plaques in chronic occlusions were predominantly hypodense, a nd 44 % were characterized by a multilayered plaque appearance. The el astic recoil was higher in multilayered plaques than in other plaques (46 +/- 19 % vs. 34 +/- 15 %; p < 0.05). Based on the quantitative ult rasound measurement after the initial balloon dilatation, it appeared that the initial balloon was undersized in 54 %. The lumen area in pat ients with balloon angioplasty alone was increased from 4.02 +/- 1.34 mm(2) to 5.49 +/- 1.47 mm(2) and in the stented patients from 3.58 +/- 1.04 mm(2) to 7.10 +/- 1.92 mm(2). The recurrence rate in patients wi th balloon angioplasty was 48 % with 24 % reocclusions. Patients with recurrence had a slightly lower lesion area (3.97 +/- 1.41 mm(2) vs. 4 .71 +/- 1.44 mm(2); n.s.) and minimum diameter (1.82 +/- 0.31 mm vs. 2 .14 +/- 0.40 mm; p < 0.05) after dilatation. In stented patients the r ecurrence rate was 27 % with two early stent thrombosis (6.7 %) and no late reocclusion. In patients with recurrence the achieved stent area was significantly smaller than in those without restenosis (5.71 +/- 0.90 mm(2) vs. 7.59 +/- 1.96 mm(2); p < 0.01), and the degree of vascu lar remodeling at the site of the occlusion was less pronounced. Intra coronary ultrasound showed sonographic plaque characteristics in chron ic occlusions which responded poorly to balloon dilatation alone. Sten t implantation improved considerably the luminal area gain and could r educe the long-term outcome. To further improve the recurrence rate in stents, an optimized stent expansion should be achieved, and intracor onary ultrasound could provide an ideal tool for this purpose.