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 lesions of these patients, however, has never been quantified. METHODS AND RESULTS We measured the ACE activity of vascular tissue obtained by directional coronary atherectomy in patients with acute coronary syndrome (n=17) and in patients with stable ischemic heart disease (n=36), with and without restenosis. The ACE activity of the culprit coronary lesions was 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 ischemic heart disease with restenosis (n=11, 0.19+/-0.05 nmol. min(-1). mg protein(-1)) when compared with those patients with ischemic heart disease 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 activity did not differ significantly among the patients. CONCLUSIONS The present study demonstrates increased ACE activity in culprit lesions in acute coronary syndrome, indicating that enhanced ACE activity is related to the causative mechanism of active coronary lesions.