Role of dobutamine-stress echocardiography in prediction of clinical and functional improvement after coronary artery bypass grafting in patients with low ejection fraction

Background
The aim of this study was to assess the results after coronary artery bypass graft (CABG) in patients with reduced ejection fraction (EF; ≤40%) but viable myocardium and to determine the possible predictors of postoperative outcome, depending on preoperative dobutamine-stress echocardiography (DSE) results.
Patients and methods
The study included 110 patients who underwent isolated elective on-pump CABG with left ventricular ejection fraction (LVEF) less than 40%. This study was conducted at the Department of Cardiothoracic Surgery in Ain Shams University Hospital, Nasr City Insurance Hospital, and Minia University Hospital. This prospective observational study was conducted over 1 year with a follow-up period of 6 months.
Results
The study approved a statistically significant increase in New York Heart Association class I and Canadian Cardiovascular Society grades I and II. Changes in the findings of trans-thoracic echocardiography postoperatively and at the end of the follow-up period in survivors compared with preoperative values were statistically significant in the form of improvements in LV dimensions, LVEF, and segmental wall motion abnormalities. On univariable analysis of the predictors of in-hospital mortality, the significant predictors were age more than 60 years, peak wall motion score index on DSE more than 1.5, improvement of LVEF on DSE less than 10%, insertion of intra-aortic balloon pump (intraoperative or postoperative), and incomplete revascularization. On multivariable analysis of the predictors of in-hospital mortality, insertion of intra-aortic balloon pump was the only significant predictor of mortality.
Conclusion
CABG for dysfunctioning but viable myocardium enhances LV recovery of function and ensures acceptable survival. The results of DSE in patients with low LVEF are predictive for clinical improvement. Therefore, assessment of wall motion score index and LVEF with dobutamine echocardiography may be the optimal means of evaluating the impact of viability on prognosis.