MORPHOLOGY OF CHRONIC CORONARY OCCLUSIONS AND RESPONSE TO INTERVENTIONAL THERAPY - A STUDY BY INTRACORONARY ULTRASOUND

Objectives. Balloon angioplasty of chronic coronary occlusions has a l ow procedural success and a high recurrence rate. Better tomographic i nsights into the lesion morphology may improve the interventional stra tegy and results. Methods. Intracoronary ultrasound was used during th e recanalizaton procedure of 45 chronic coronary occlusions (2 weeks t o 14 months; average 3.4 months) to determine the lesion morphology an d to assess the angioplasty result. The luminal area and the plaque bu rden were measured proximal and distal to the occlusion, and within th e occlusion. The ultrasonographic characteristics of the occlusive les ions were compared to 45 nonocclusive lesions of age-matched patients with stable angina pectoris. Results. Occlusive lesions were more ofte n echodense as compared to nonocclusive lesions (35% vs. 20%; p=0.10). In chronic occlusions a multi-layered plaque morphology was observed in 22%, and this morphology was not found in nonocclusive lesions. Ang iographic characteristics were not related to the ultrasonographic mor phology of the lesion. Despite similar vessel areas in occlusive and n onocclusive lesions, the balloon size selected according to the angiog raphic image was underestimated in occlusive lesions. Based on the qua ntitative ultrasound measurement the balloon size was increased from 2 .6+/-0.3 mm to 3.3+/-0.5 mm in 53% of the lesions. This resulted in an increase of the luminal area from 3.51+/-0.92 to 5.08+/-1.43 mm(2) (p <0.001). The acute recoil after balloon angioplasty was similar (34+/- 18%) in hypodense and echodense plaques, but was significantly higher in lesions with a multi-layered plaque morphology (49+/-22%; p<0.05). In 19 patients with severe dissections or extreme acute recoil (residu al stenosis>50%) the use of a stent increased the luminal area from 3. 94+/-0.81 to 7.51+/-1.71 mm(2) (p<0.001). Conclusion. Intracoronary ul trasound demonstrated a multi-layered plaque morphology in one fourth of the chronic occlusions. This type of plaque was associated with a s ignificant acute recoil. The presence of diffuse atherosclerosis in ne ighbouring segments of chronic coronary occlusions leads to underestim ation of the balloon size. Quantitative assessment by intracoronary ul trasound helped to optimize the balloon size leading to a significant luminal area gain. The detection of excessive acute recoil should be c onsidered an indication for stent deployment.