CORONARY-ARTERY RESTENOSIS AFTER BALLOON ANGIOPLASTY IN HUMANS IS ASSOCIATED WITH CIRCUMFERENTIAL CORONARY CONSTRICTION

Therapies that inhibit intimal hyperplasia do not prevent restenosis a fter coronary artery balloon angioplasty, suggesting that additional m echanisms may be responsible for restenosis in humans. Using an intrav ascular ultrasound (Hewlett-Packard Sonos Intravascular Imaging System ), 3.5F, 30-MHz (Boston Scientific) monorail imaging catheter, we stud ied 17 patients with clinical and angiographic restenosis at an averag e (mean+/-SD) of 7+/-6 months after balloon angioplasty (13 men: age, 71+/-10 years; 12 left anterior descending coronary arteries, 4 right coronary arteries, and 1 left circumflex coronary artery). The lumen a rea (LA), vessel wall area (VWA), and total cross-sectional area (CSA) within the external elastic lamina were measured at the restenosis si te and at proximal and distal reference sites, which were defined as a djacent segments with the least amount of plaque. Consistent with coro nary angiography findings, decreased LA at the restenotic site was det ected in all 17 patients. The unique finding was that total CSA at the restenotic site was significantly decreased compared with both proxim al and distal reference sites (10.1+/-2.4 versus 14.8+/-3.2 mm(2) and 10.1+/-2.4 versus 13.8+/-3.1 mm(2), respectively, P<.001), whereas VWA (intima plus media) was slightly increased at the angio plasty site c ompared with both proximal and distal reference sites (8.0+/-2.3 versu s 7.6+/-2.3 mm(2) and 8.0+/-2.3 versus 6.7+/-2.3 mm(2), respectively, P=NS). Eighty-three percent of the loss in LA at the restenotic site w as due to constriction of the total CSA, while the increase in VWA at the restenotic site accounted for only a 17% loss in LA. We then compa red these results with the morphology of coronary artery segments in 1 4 patients without restenosis. These coronary artery segments had been previously treated with balloon angioplasty (7+/-5 months). Unlike th at in restenotic lesions, the total CSA within the external elastic la mina at the sites of previous angioplasty was similar to that in dista l and proximal reference sites (P=NS). Significant and consistent redu ction in arterial CSA, with a minor increase in VWA, characterizes hum an coronary lesions that cause angiographic restenosis. These data sug gest that in humans, ''recoil'' and/or vascular contraction with heali ng in response to balloon injury is a major contributor to restenosis after balloon angioplasty.