The present study is aimed at checking effects exerted by captopril on human myocardial ACE system (ACE-T) as well as the role played by tissue ACE-inhibition in reducing reperfusion damage. A human experimental model was used during cardioplegia due to aortocoronary bypass graft (CABG): 54 patients with coronary artery disease affecting 3 vessels having suffered from acute anterior myocardial infarction, homogeneous as far as ejection fraction (35-55%), number of grafts (3), clamping time, age and sex, were randomised in a double blind experiment, and were given captopril or placebo: 4 mg/l captopril were mixed into the cardioplegic solution with blood according to Buckberg, 8 blood samples were obtained from each patient and norepinephrine, epinephrine were assayed using an HPLC technique. Angiotensin 1 was assayed by RIA. CK was assayed as well (U/L). Blood samples were taken during CABG: pre-pump sample; pump sample; pump preclamping sample; coronary sinus sample; warm reperfusion sample; coronary sinus during warm reperfusion; after clamping sample; after cannulation.
Results: captopril group (29 patients): angiotensin 1:8.15; 6.9; 7.45; 8.66; 8.93; 8.70; 9.07; 9.40 versus placebo: 7.09; 7.43; 7.80; 9.31; 9.01; 8.35; 8.85; 8.07 mcg (all NS). Noradrenaline: captopril group: 359; 404; 329; 282; 263; 216; 310; 337 versus placebo: 439; 520; 499; 469; 526; 566; 501; 443 pg (p < 0.001). CK, captopril group: 79.9; 95.1; 100.8; 94.3; 104.2; 94.7; 108.4; 108 versus placebo: 76.2; 120.2; 135.5; 203; 225; 272; 247; 228.7 U/L (p < 0.01). Epinephrine values showed no significant difference between the 2 groups. Norepinephrine and CK decrease as well as angiotensin I increase in treated patients as compared to controls suggest some effect exerted by captopril ACE-T and its capability of reducing reperfusion damage and recommend its use for heart protection during CABG.