Effect of coronary artery bypass graft surgery on left ventricular systolic function.

BACKGROUND: Changes in left ventricular (LV) systolic function in response to coronary artery bypass grafting (CABG) have not been fully assessed.

METHODS: Between January 2001 and December 2014, 2,838 consecutive patients underwent isolated CABG at the Minneapolis Veterans Affairs Health Care System. Of these, 375 had echocardiographic assessment of LV function before (within 6 months) and after (3 to 24 months) CABG and were included in this analysis.

RESULTS: While the mean LV ejection fraction (LVEF) did not change following CABG [(49±13)% vs . (49±12)%, P=0.51], LVEF decreased in the subgroup with normal (≥50%) pre-operative LVEF [from (59±5)% to (56±9)%, P<0.001] and improved in those with decreased (<50%) pre-operative LVEF [from (36±9)% to (41±12)%, P<0.001]. There was a significant reduction in LV internal diameter during end-diastole (LVIDd) (5.4±0.8 vs . 5.3±0.9, P=0.002) and an increase in left atrial diameter (LAD) (4.4±0.7 vs . 4.6±0.7, P<0.001). There were no perioperative changes in LV internal diameter during end-systole, LV mass, posterior wall thickness, or septal wall thickness. LVEF improved by >5% in 24% of the study population, did not change (+/- 5%) in 55%, and worsened by >5% in 21%. Patients with improved EF were less often diabetic and had lower pre-operative LVEF, and greater LV dimensions at baseline.

CONCLUSIONS: After CABG, there was a decrease in LVIDd and an increase in LAD. Also, a decrease in LV systolic function with CABG was observed in patients with normal pre-operative LVEF and an improvement in LV systolic function was observed in patients with decreased pre-operative LVEF.