Assessment of left ventricular contractile characteristics following coronary artery bypass grafting

The present study was designed to assess a left ventricular function, particularly contractile characteristics following coronary artery bypass grafting (CABG). The subject was 29 post-CABG patient consisting of 4 groups; 6 patients with complete revascularization (CR) and no myocardial infarction (MI) (CR.MI(-) group), with CR and MI (CR.MI(+) group), 5 with incomplete revascularization (IR) and no MI (IR.MI(-) group) and 8 with IR and MI (IR.MI(+) group). Ejection fraction (EF), systolic pressure/end-systolic volume index (SP/ESVI) and end-systolic volume index (EDVI) were evaluated utilizing radionuclide angiography at rest and during exercise (Ex). Increase of SP/ESVI and EF and no change of EDVI during Ex were observed in CR.MI(-) group. Increase of SP/ESVI and no change of EF and EDVI in CR.MI(+) group, no change of SP/ESVI, EF and EDVI in IR.MI(-) group and no change of SP/ESVI and EDVI and decrease of EF in IR.MI(+) group were observed. The SP/ESVI and EF of CR.MI(-) group were respectively highest among 4 groups and showed no difference compared with control group during Ex. Ex-induced increase ratio of SP/ESVI had linear correlations with Ex-induced increment of EF (r = 0.81, p less than 0.001) and Ex-induced increase ratio of EFVI (r = 0.54, p less than 0.005). It is concluded that both CR and no MI lead to normalization of EF and SP/ESVI during Ex. Furthermore, in the case of poor contractile reserve, systolic function may deteriorate in spite of increased preload during Ex.