Increased angiotensin-converting enzyme activity in coronary artery specimens from patients with acute coronary syndrome

Background-Angiotensin-converting enzyme (ACE) inhibitors are effective in the secondary prevention of ischemic heart disease, but they do not reduce the rate of restenosis. Vascular ACE activity in the culprit coronary lesio ns of these patients, however, has never been quantified. Methods and Results-We measured the ACE activity of vascular tissue obtaine d by directional coronary atherectomy in patients with acute coronary syndr ome (n=17) and in patients with stable ischemic heart disease (n=36), with and without restenosis, The ACE activity of the culprit coronary lesions wa s significantly increased in patients with acute coronary syndrome (0.87+/- 0.12 nmol . min(-1) . mg protein(-1); P<0.01) but not in patients with isch emic heart disease with restenosis (n=11, 0.19+/-0.05 nmol <bullet> min(-1) . mg protein(-1)) when compared with those patients with ischemic heart di sease without restenosis (n=25, 0.20+/-0.05 nmol . min(-1) . mg protein(-1) ). There was no difference between the ACE activity of the coronary tissue of the in-stent (n=5) and stent-unrelated (n=6) restenosis patients (0.24+/ -0.10 versus 0.15+/-0.04 nmol . min(-1) . mg protein(-1)). Serum ACE activi ty did not differ significantly among the patients. Conclusions-The present study demonstrates increased ACE activity in culpri t lesions in acute coronary syndrome, indicating that enhanced ACE activity is related to the causative mechanism of active coronary lesions.