ABNORMAL CORONARY VASOMOTION IN HYPERTENSION - ROLE OF CORONARY-ARTERY DISEASE

Objectives. This study sought to evaluate the effect of dynamic exerci se on coronary vasomotion in hypertensive patients in the presence and absence of coronary artery disease. Background. Endothelial dysfuncti on with abnormal coronary vasodilation in response to acetylcholine ha s been reported in patients with arterial hypertension. Methods. Coron ary artery dimensions of a normal and stenotic vessel segment were det ermined in 64 patients by biplane quantitative coronary arteriography at rest and during supine bicycle exercise. Patients were classified i nto two groups: 20 patients without evidence of coronary artery diseas e (10 normotensive, 10 hypertensive [group 1]) and 44 patients,vith co ronary artery disease (26 normotensive, 18 hypertensive [group 2]). Bo th groups were comparable with regard to clinical characteristics, ser um cholesterol levels, body mass index, exercise capacity and hemodyna mic data. Results. Mean aortic pressure was significantly higher in hy pertensive than normotensive patients. Exercise-induced vasodilation o f the normal vessel segment was similar in normotensive and hypertensi ve patients without coronary artery disease (group 1), namely, +19% ve rsus +20%. However, in hypertensive patients with coronary artery dise ase, exercise-induced vasodilation was significantly less in both norm al and stenotic vessel segments than in normotensive subjects (+1% vs. +20% for normal [p < 0.003] and -20% vs. -5% for stenotic vessels [p < 0.025]), Administration of 1.6 mg of sublingual nitroglycerin at the end of exercise led to a normalization of the vasodilator response in normotensive as well as hypertensive patients. However, this response became progressively abnormal in group 2 when coronary artery disease was present. Conclusions. In the absence of coronary artery disease, the vasomotor response to exercise is normal in both normotensive and hypertensive patients. However, in hypertensive patients with coronary artery disease, an abnormal response of the coronary vessels can be o bserved, with a reduced vasodilator response to exercise in normal art eries but an enhanced vasoconstrictor response in stenotic arteries. T his behavior of the epicardial vessels during exercise suggests the oc currence of endothelial dysfunction (i.e., functional defect) that is not evident in the absence of coronary artery disease. Nitroglycerin r everses impaired coronary vasodilation, but this effect is blunted in the presence of coronary artery disease (i.e., structural defect).