[en] From May 1983 to December 1984, 30 aorto-coronary bypasses (A-CBs) distal to the complete occlusion were attempted in 19 cases who had angina pectoris (12 stable and 7 unstable angina) and were diagnosed as having viable muscle in the distal area of occlusion by thallium-201 stress-myocardial scintigraphy. Quality of distal lumen was divided into 4 groups by preoperative coronary arteriogram according to the following grading system, Group A (G-A); normal distal calibre of more than 1.5 mm, Group B (G-B); small calibre of less than 1.5 mm, however probably graftable, Group C (G-C); threadlike distal lumen, with seemingly poor graftability, Group D (G-D); no opacification of distal lumen. A-CBs were successfully placed on 4/4 (100 %) of G-A, 12/12 (100 %) of G-B, 7/10 (70 %) of G-C and 0/4 (0 %) of G-D. The average calibre was 1.94 mm in G-A, 1.59 mm in G-B and 1.43 mm in G-C. The average graft flow was 94 ml/min in G-A, 50 ml/min in G-B and 43 ml/min in G-C. Graft patency in 1 - 2 months after A-CBs was 4/4 (100 %) in G-A, 11/12 (91 %) in G-B and 7/7 (100 %) in G-C. Although postoperatively 1 case whose ejection fraction was 0.17 died and without medication 3 cases still had effort angina, 15 cases have become free from angina with improvement of LVESVI, LVEF, CI and initial imaging of stress-myocardial scintigram. In conclusion, even when a coronary artery is occluded completely, if distal coronary artery has proper lumen for A-CBs and viable muscle remains, A-CBs distal to the occlusion is worth-while. A-CBs were successfully performed in 70 % of G-C where preoperative estimation for graftability was seemingly poor. Thallium-201 stress-myocardial scintigraphy is a reliable method to prove viable muscle in complete coronary artery occlusion. (author)