Abstract

Objectives: To investigate the effect of enalapril, losartan, and surgical coronary revascularisation on endothelial function, and the role of the angiotensin converting enzyme (ACE) insertion (I)/deletion (D) polymorphism.

Design: Randomised, controlled, blinded end point study.

Setting: University tertiary referral cardiac centre.

Patients and interventions: 49 men awaiting coronary artery bypass grafting (CABG) were randomly assigned to treatment with losartan, enalapril, or control for two months before and three months after surgery.

Main outcome measures: Endothelial function was blindly analysed by brachial artery flow mediated dilatation (FMD) and ACE I/D genotype was determined.

Results: FMD was impaired at baseline (1.0–1.7%) and after five months had improved to 5.2% with enalapril (p  =  0.015), 5.0% with losartan (p  =  0.0004), and 3.0% with CABG alone (p  =  0.05). Patients with the II genotype had lower baseline FMD than those with DI or DD (0.1% v 1.7%, p  =  0.038) and after enalapril or losartan treatment had greater improvement in FMD (mean (SEM) 7.1 (1.1)%) than patients with DI (3.1 (1.3)%, p  =  0.024) or DD genotype (3.1 (1.1)%, p  =  0.02).

Conclusions: Enalapril and losartan, with surgical coronary revascularisation, significantly improve systemic endothelial function. Revascularisation alone produces a quantitatively smaller, but still significant, improvement. The ACE genotype significantly modulates this response. Patients with the II genotype have a more pronounced impairment in endothelial function at baseline and a greater improvement in response to treatment with these agents.