CORONARY VASOMOTION AFTER PERCUTANEOUS TRANSLUMINAL CORONARY ANGIOPLASTY DEPENDS ON THE SEVERITY OF THE CULPRIT LESION

Objectives. This study sought to evaluate coronary vasomotor response to percutaneous transluminal coronary angioplasty (PTCA) and its influ ence on proximal and distal vessel diameters with regard to stenosis s everity and coronary blood flow. Background. Coronary vasoconstriction of the distal vessel segment has been reported after PTCA, This vasoc onstrictive effect was thought to be due to balloon-induced injury of the vessel wall, with release of local vasoconstrictors or stimulation of the sympathetic system with release of catecholamines, or both. Me thods. Thirty-nine patients were prospectively studied before and afte r PTCA, Patients were classified into two groups according to the seve rity of the culprit lesion: group 1 = greater than or equal to 70% to less than or equal to 85% diameter stenosis (n = 23); and group 2 = >8 5% to less than or equal to 95% diameter stenosis (n = 16), The corona ry vessel diameter of the proximal and distal vessel segments as well as the minimal lumen diameter were determined by quantitative coronary angiography, In a subgroup of 16 patients, basal and maximal coronary flow velocity was measured before and after PTCA with the Doppler Flo Wire system. Results. The groups were comparable with regard to age, g ender, serum cholesterol levels and medical therapy. The proximal vess el segment remained unchanged after PTCA in group 1 ([mean +/- SD] 0.9 +/- 3.5%, p = 0.8) but showed vasodilation in group 2 (+13.7 +/- 3.6% , p < 0.05), However, the distal segment showed vasoconstriction in gr oup 1 (-6.7 +/- 2.0%, p < 0.01) and vasodilation in group 2 (+31 +/- 8 .0%, p < 0.01). A significant correlation was found between the change in distal vessel diameter after PTCA and stenosis severity (r = 0.61, p < 0.0001). Changes in blood flow were directly correlated to stenos is severity (r = 0.85, p < 0.002); that is, rest flow increased after PTCA in narrow lesions but remained unchanged in moderate lesions, The diameter changes in the distal vessel segment after PTCA were signifi cantly related to flow changes (r = 0.90, p < 0.0001), Coronary disten ding pressure of the distal vessel segment increased significantly in both groups; however, this increase was significantly greater in group 2 than in group 1 (55 +/- 4 vs. 14 +/- 3 mm Hg, p < 0.0001). Conclusi ons. Coronary vasomotion of the proximal and distal vessel segments af ter PTCA depends on the severity of the culprit lesion; that is, vasoc onstriction of the distal segment is found in patients with moderate l esions and vasodilation in those with severe lesions. Thus, vasomotion of the post-stenotic vessel segment depends on the severity of the cu lprit lesion and is influenced by changes in coronary flow or distendi ng pressure, or both. (C) 1997 by the American College of Cardiology.