Different response to balloon angioplasty of carotid and coronary arteries: effects on acute platelet deposition and intimal thickening

PTCA is a well-established intervention to reduce the severity of atheroscl erotic coronary stenosis. Its primary success rate is seriously handicapped by the high incidence of late restenosis. Given the clinical and social im portance of this proliferative process, new strategies are needed to preven t or reduce restenosis. Several animal models as well as different arteries have been used to study neointimal proliferation after arterial injury. A number of agents have shown to reduce neointimal proliferation after arteri al injury in the carotids and iliac arteries of rodent models. Unfortunatel y, these results have not been replicated in humans. We have compared the a cute and late response to vascular injury of the carotid and coronary arter ies in the pig. Arterial injury was induced by performing balloon angioplas ty of the carotid (elastic) and coronary (muscular) arteries in swine. Acut e platelet-thrombus formation was evaluated by quantitation of Indium-label ed platelets deposited on the injured segments 1 h after procedure. Measure ment of intimal area was performed by morphometry of the most stenotic cros s-section at 28 days after balloon angioplasty. Platelet deposition after m im and severe injury in carotids (4 +/- 1 and 56 +/- 13 x 10(6) platelets/c m(2), respectively) and coronaries (15 +/- 5 and 141 +/- 20 x 10(6) platele ts/cm(2), respectively) are significantly greater in deep, than in mild inj ury (P < 0.005), and significantly greater in coronary than in carotid arte ries after deep injury (P < 0.05). Likewise, late neointima formation was s ignificantly greater (P < 0.05) after mild and severe injury in coronary (1 7 +/- 0.5 and 56 +/- 2%, respectively) than in carotid arteries (5 +/- 0.5 and 12 +/- 1%, respectively). Acute platelet-thrombus formation and late ne ointimal thickening are modulated by the degree of injury induced during th e interventions; and after disruption of the internal elastic lamina, coron ary arteries always had significantly more acute thrombus and neointimal th ickening. This study emphasizes the importance of the animal species, the t ype of injury and the artery chosen for studies on restenosis post interven tions. (C) 1998 Published by Elsevier Science Ireland Ltd. All rights reser ved.