INTRAVASCULAR ULTRASOUND IMAGING OF ANGIOGRAPHICALLY NORMAL CORONARY SEGMENTS IN PATIENTS WITH CORONARY-ARTERY DISEASE

Intravascular ultrasound imaging (IVUS) constitutes a new diagnostic t echnique that provides unique information concerning arterial wall str ucture and luminal dimensions. To assess the anatomic features of angi ographically normal coronary arteries in patients with coronary artery disease, 25 patients (aged 61 +/- 9 years) underwent an IVUS examinat ion before coronary angioplasty. A mechanical (20 MHz) IVUS system was used. Atherosclerotic plaques were identified by IVUS as well-defined structures of variable echodensity protruding into the coronary lumen or disrupting normal coronary wall architecture. Five (20%) patients had minor angiographic irregularities proximal to the target lesion, a nd all 5 had plaque on IVUS. In the remaining 20 patients the coronary segments proximal to the target lesion were angiographically normal. Of these, IVUS demonstrated the presence of plaque in 16 (80%) patient s at 19 different angiographic sites (3 lipidic, 13 fibrotic, 3 calcif ied). Fifteen plaques had a semilunar appearance and did not disrupt l uminal contour, but four clearly protruded into the coronary lumen. Si x plaques were located in the left main artery, 4 in the left anterior descending artery, 4 in the left circumflex artery, 4 in the right co ronary artery, and 1 in a vein graft. On quantitative angiography, lum inal diameter, at sites angiographically normal but with plaque on IVU S, was 3.6 +/- 1 mm. At these sites, both minimal luminal diameter (3. 5 +/- 1 mm) and maximal luminal diameter (4.3 +/- 1 mm) on IVUS correl ated (r = 0.59 and r = 0.61, respectively) with angiographic measureme nts (p < 0.05). No complications resulted from the IVUS study. Thus in patients with coronary artery disease (1) the atherosclerotic involve ment of the arterial wall extends beyond the angiographic lesion site; (2) IVUS frequently reveals plaque at sites with a normal angiographi c appearance; and (3) these plaques usually have a semilunar shape and do not disrupt luminal contour.