Coronary artery vasoconstriction after successful single angioplasty of the left anterior descending artery

Abstract

Percutaneous transluminal coronary angioplasty is associated with spontaneous transient vasoconstriction. The mechanisms by which coronary vasoconstriction occurs distally to a successful dilated stenosis after coronary artery angioplasty are still unknown. The present study was planned to investigate the effect of successful coronary artery angioplasty on coronary vasomotion distal to a dilated stenosis and in the control vessel and the role of α-adrenergic receptors on coronary vasomotion after successful coronary artery angioplasty. We prospectively studied 32 consecutive patients scheduled for elective single coronary artery angioplasty of the left anterior descending coronary artery. Only aspirin, 325 mg, or nitroglycerin was allowed in the week before the study; no premedication with diazepam or other drugs was given. In group 1 (control patients, n = 20), quantitative coronary angiography was pertormed in the control state; 5 and 15 minutes after coronary artery angioplasty; and after intracoronary nitroglycerin infusion, 300 μg. In group 2 ( n = 12), intracoronary phentolamine, 2 mg, was infused regionally through the balloon catheter before the coronary artery angioplasty, and coronary angiography was pertormed at baseline, 15 minutes after balloon deflation, and after nitroglycerin infusion. In group 1, constriction of the coronary segment distal to a dilated stenosis (2.4 ± 0.8 to 2.1 ± 0.6 mm, −14.6% vs baseline; p < 0.05) and of the circumflex coronary artery segment (2.8 ± 0.7 to 2.5 ± 0.6 mm, −10.7% vs baseline, p < 0.05) occurred 15 minutes after coronary artery angioplasty. The degree of vasoconstriction was not correlated with the lesion severity before coronary artery angioplasty. In group 2, nonselective α-adrenergic blockade prevented distal vasoconstriction after coronary artery angioplasty (2.1 ± 0.4 vs 2.2 ± 0.4 mm; difference not significant), whereas significant vasoconstriction was observed in the control circumflex segments (2.7 ± 0.6 vs 2.4 ± 0.7 mm; p < 0.05). After successful coronary artery angioplasty of the left anterior descending coronary artery, constriction of the coronary segment distal to the site of balloon dilation and of the control segment in the circumflex coronary artery was observed. The degree of vasoconstriction of the segment distal to the stenosis was not correlated with lesion severity before coronary artery angioplasty. Pretreatment with regional α-adrenoceptor blockade abolished the coronary vasoconstriction. Therefore a generalized mechanism and α-adrenergic-mediated constriction may participate in the abnormal vasomotor changes after successful angioplasty. These findings may provide insight into the mechanisms of coronary vasoconstriction after coronary artery angioplasty.