Improvement of myocardial blood flow to ischemic regions by angiotensin converting enzyme inhibition with quinaprilat IV - A study using [O-15] waterdobutamine stress positron emission tomography

OBJECTIVES This study was designed to analyze the effects of acute angioten sin-converting enzyme (ACE) inhibition on myocardial blood flow (MBF) in co ntrol and ischemic regions. BACKGROUND Although animal studies indicate an improvement of MBF to ischem ic regions after ACE inhibition, this effect has not been conclusively demo nstrated in patients with coronary artery disease. METHODS Myocardial blood flow was analyzed in ischemic and nonischemic regi ons of 10 symptomatic patients with coronary artery disease using repetitiv e [O-15] water positron emission tomography at rest and during maximal dobu tamine stress before and after ACE inhibition with quinaprilat 10 mg IV. To exclude the possibility that repetitive ischemia may cause an increase in MBF, eight patients underwent the same protocol without quinaprilat (placeb o patients). RESULTS Rate pressure product in control and quinaprilat patients was compa rable. In placebo patients, repetitive dobutamine stress did not change MBF to ischemic regions (1.41 +/- 0.17 during the first stress vs. 1.39 +/- 0. 19 ml/min/g during the second stress, p = 0.93). In contrast, MBF in ischem ic regions increased significantly after acute ACE inhibition with quinapri lat during repetitive dobutamine stress (1.10 +/- 0.13 vs. 1.69 +/- 0.17 ml /min/g, p < 0.015). Dobutamine coronary reserve in ischemic regions remaine d unchanged in placebo patients (1.07 +/- 0.11 vs. 1.10 +/- 0.16, p = 0.92) , but increased significantly after quinaprilat (0.97 +/- 0.10 vs. 1.44 +/- 0.14, p < 0.002). Total coronary resistance decreased after ACE inhibition (123 +/- 19 vs. 71 +/- 10 mm Hg.min.g/ml, p < 0.02). CONCLUSIONS Angiotensin-converting enzyme inhibition by quinaprilat signifi cantly improves MBF to ischemic regions in patients with coronary artery di sease. (J Am Coll Cardiol 1999;34: 1005-11) (C) 1999 by the American Colleg e of Cardiology.