Comparison of suppression of the circulating and vascular renin-angiotensin system by enalapril versus trandolapril in chronic heart failure.

Experimental studies suggest that angiotensin-converting enzyme (ACE) inhibitors with high tissue affinity confer a greater degree of vascular renin-angiotensin system suppression than those with low tissue affinity despite similar suppression of the circulating renin-angiotensin system. To test this hypothesis in a clinical setting, we randomized subjects with chronic heart failure to receive the low tissue affinity ACE inhibitor enalapril or the high tissue affinity ACE inhibitor trandolapril, and assessed the degree of circulating and vascular renin-angiotensin system suppression. Vascular renin-angiotensin system suppression was determined by measuring the pressor response to intravenous injections of angiotensin I.