INFLUENCE OF CORONARY ATHEROSCLEROTIC REMODELING ON THE MECHANISM OF BALLOON ANGIOPLASTY

Objectives Intracoronary ultrasonography was used to assess coronary a rteries before and after balloon percutaneous transluminal coronary an gioplasty (PTCA) to determine whether the mode of coronary atheroscler otic remodeling affects the mechanism of balloon dilation. Background Coronary arteries may enlarge or shrink in response to atherosclerotic plaque development. The effect Of coronary remodeling on the mechanis m of balloon PICA has not yet been studied. Methods Forty-one patients with 47 native de novo coronary artery lesions were studied with a 30 MHz intracoronary ultrasound catheter before and after balloon PTCA. Images were analyzed at the lesion site and the adjacent reference seg ments. At each site the lumen, vessel, and plaque area and the percent area stenosis were measured. Lesions were separated into two groups b ased on relative vessel area (lesion vessel area/reference vessel area ). A relative vessel area >1.0 defines adaptive enlargement(group 1, n = 25), whereas a relative vessel area less than or equal to 1.0 refle cts coronary shrinkage (group 2, n = 22). Regression analysis examined whether elastic recoil and the PICA balloon/vessel area ratio correla ted. Results After balloon PTCA was performed, both the enlargement an d shrinkage groups had similar gains in luminal area (2.3 +/- 1.8 mm(2 ) [mean +/- SD] vs 2.8 +/- 1.7 mm(2), p = 0.32), reduction in percent stenosis (-19.2% +/- 11.5% vs -14.4 +/- 12.7, p = 0.18), and final lum en area (4.9 +/- 1.7 mm(2) vs 4.7 +/- 1.9 mm(2), p = 0.73). However, t he mechanism of luminal enlargement was different in each group. Reduc tion in plaque area was significantly greater in the enlargement group (group 1, -2.0 +/- 1.7 mm(2) vs group 2, 0.04 +/- 2.2 mm(2); p = 0.00 1), whereas increased vessel area was more important in the shrinkage group (group 1, 0.8 +/- 1.5 mm(2) vs group 2, 2.4 +/- 2.3 mm(2); p = 0 .009). Positive correlation was seen between elastic recoil and the ba lloon/vessel area ratio in lesions with vessel enlargement (r = 0.80, p < 0.0001). No such correlation was observed in shrinkage vessels (r = 0.28, p = 0.21). Conclusions The acute luminal gain after balloon PT CA is similar regardless of the type of coronary remodeling. However, the mode of remodeling affects the mechanism of balloon dilation such that enlargement vessels exhibit plaque compression, whereas shrinkage arteries demonstrate vessel stretch. The post-PTCA elastic recoil cor relates linearly to the balloon/vessel area ratio in arteries that hav e undergone adaptive enlargement.