Inhibition of angiotensin converting enzyme cannot prevent increases in angiotensin II production in coronary circulation

Objective-To determine whether inhibition of angiotensin converting enzyme (ACE) can prevent angiotensin II production in the coronary circulation induced by percutaneous transluminal coronary angioplasty (PTCA) in patients with myocardial ischaemia. Design, patients-41 patients who underwent elective PTCA and six control subjects who received diagnostic coronary angiography were studied. Patients were divided into two groups according to the chronic administration of ACE inhibitors (group A, 15 patients treated with ACE inhibitors; group B, 26 patients without ACE inhibitors). Blood samples were drawn through catheters placed in the aorta and coronary sinus before and 24 hours after PTCA. Results-Mean levels of ACE activity in the aorta were significantly lower in patients in group A than in group B. However, mean angiotensin II concentrations in the aorta were not significantly different. between the two groups. Differences in basal angiotensin II concentrations between the coronary sinus and aorta, which reflected basal angiotensin II production in the coronary circulation, were not significant among group A, group B, and control subjects. The production of angiotensin II in the coronary circulation was significantly increased 24 hours after PTCA in both group A and group B to the same extent. No significant changes were observed in control subjects 24 hours after diagnostic coronary angiography. Conclusions-This study revealed that inhibition of ACE activity by ACE inhibitors could not prevent increases in angiotensin II production in the coronary circulation induced by PTCA.