S. Nakamura et al., AN EXPLANATION FOR DISCREPANCY BETWEEN ANGIOGRAPHIC AND INTRAVASCULARULTRASOUND MEASUREMENTS AFTER PERCUTANEOUS TRANSLUMINAL CORONARY ANGIOPLASTY, Journal of the American College of Cardiology, 25(3), 1995, pp. 633-639
Objectives. This study attempted to determine why there is a discrepan
cy between angiographic and intravascular ultrasound measurements afte
r coronary balloon angioplasty. Background. Previous studies have show
n a poor correlation between angiographic and intravascular ultrasound
measurements after percutaneous coronary balloon angioplasty. Methods
. After successful balloon angioplasty, 91 lesions in 84 patients were
studied by intravascular ultrasound. Plaque morphology on intravascul
ar ultrasound was classified as demonstrating a superficial injury if
there was either no fracture or only a small tear that did not extend
to the media versus a deep injury defined as the presence of a plaque
fracture that reached the media. Measurements of minimal lumen diamete
r were compared between angiography and intravascular ultrasound. Resu
lts. On ultrasound imaging, a superficial injury pattern was observed
in 44 lesions, whereas a deep injury was seen in 47 lesions. There wer
e no statistical differences at baseline in patient or lesion characte
ristics. In the superficial injury group there was a significant corre
lation between angiography and intravascular ultrasound for minimal lu
men diameter (r = 0.67) and lumen cross-sectional area (r = 0.69). In
the deep injury group there was a poor correlation for minimal lumen d
iameter (r = 0.05) and lumen cross-sectional area (r = 0.28). After ba
lloon angioplasty, the angiographic appearance showed a normal contour
in 34%, the presence of dissection in 38% or a hazy appearance in 23%
. On ultrasound imaging after angioplasty, the superficial injury grou
p comprised 65% of lesions with a normal angiographic appearance and 6
7% of lesions with a hazy appearance, whereas 77% of lesions with an a
ngiographic diagnosis of dissection were in the deep injury group by u
ltrasound (p = 0.0005). Conclusions. These observations suggest that t
he discrepancies between angiographic and ultrasound measurements are
due to differences in plaque morphology created by balloon dilation. S
uperficial injuries demonstrate similar results by angiography or ultr
asound, whereas a deep injury to the plaque produces a difference in m
easurements between angiography and ultrasound. When angiography revea
ls a dissection, there is a high probability that intravascular ultras
ound will demonstrate a plaque fracture extending to the media.