Coronary blood flow, metabolism and function in dysfunctional viable myocardium before and early after surgical revascularization

Objectives: To assess the link between perfusion, metabolism, and function in viable myocardium beforeand early after surgical revascularisation.Design: Myocardial blood flow (MBF, thermodilution technique), metabolism (lactate, glucose, and freefatty acid extraction and fluxes), and function (transoesophageal echocardiography) were assessed inpatients with critical stenosis of the left anterior descending coronary artery (LAD) before and 30 minutesafter surgical revascularisation.Setting: Tertiary cardiac centre.Patients: 23 patients (mean (SEM) age 57 (1.7) years with LAD stenosis: 17 had dysfunctional viablemyocardium in the LAD territory, as shown by thallium-201 rest redistribution and dobutamine stressechocardiography (group 1), and six had normally contracting myocardium (group 2).Results: LAD MBF was lower in group 1 than in group 2 (58 (7) v 113 (21) ml/min, p , 0.001) beforerevascularisation and improved postoperatively in group 1 (129 (133) ml/min, p , 0.001) but not ingroup 2 (105 (20) ml/min, p = 0.26). Group 1 also had functional improvement in the LAD territory atintraoperative echocardiography (mean regional wall motion score from 2.6 (0.85) to 1.5 (0.98),p , 0.01). Oxidative metabolism, with lactate and free fatty acid extraction, was found preoperativelyand postoperatively in both groups; however, lactate and free fatty acid uptake increased afterrevascularisation only in group 1.Conclusions: MBF is reduced and oxidative metabolism is preserved at rest in dysfunctional but viablemyocardium. Surgical revascularisation yields immediate perfusion and functional improvement, andincreases the uptake of lactate and free fatty acids.