Prediction of global left ventricular function after bypass surgery in patients with severe left ventricular dysfunction - Impact of pre-operative myocardial function, perfusion, and metabolism

Aims Previous studies have compared the accuracy of various tests of viabil ity for the prediction of recovery of regional left ventricular function; g lobal left ventricular recovery has been less well studied, although it has important prognostic and functional ramifications. We sought to identify t he relative contribution of ischaemia, regional and global contractile rese rve, perfusion and metabolic function to changes in left ventricular volume s and global function after coronary artery bypass surgery in patients with severe left ventricular dysfunction. Methods and Results Dipyridamole stress Rb-82, fluorodeoxyglucose positron emission tomography and low and high-dose dobutamine-atropine stress echoca rdiography were obtained in 66 patients with left ventricular impairment. M yocardial segments were considered viable if ischaemia or either metabolic or contractile reserve were present, on positron emission tomography or dob utamine echocardiography. Resting left ventricular function was reassessed after surgery (mean 10 +/- 3 weeks) in the 59 patients who had not suffered a major peri-operative event; functional improvement was defined by a 5% i ncrement of ejection fraction. Myocardial viability was found in 37 (63%) p atients using positron emission tomography and in 42 (71%) patients using d obutamine echocardiography; post-operative functional improvement was noted in 28 (47%) patients. In univariate analyses, predictors of global post-op erative functional recovery included: the extent of viability according to positron emission tomography [OR (odds ratio): 2.08 for each additional via ble segment, 95% CI (confidence interval): 1.33-3.25, P=0.001] or dobutamin e echocardiography (OR: 2.06 for each additional viable segment, 95% CI: 1. 28-3.30, P=0.003) and the increase in ejection fraction with low-dose dobut amine (OR: 1.9 for each 1% increase in ejection fraction with low dose dobu tamine, 95% CI 1.39-2.61, P<0.0001). In a multivariate model which included evidence of viability by either technique, and change in ejection fraction with low-dose dobutamine echocardiography, only change in ejection fractio n with low-dose dobutamine echocardiography was predictive of post-operativ e left ventricular functional recovery (adjusted OR: 1.81, 95% CI: 1.30-2.5 2, P=0.0005). Conclusion Among patients with severe left ventricular dysfunction who are referred for surgical revascularization, the overall accuracies of positron emission tomography and dobutamine echocardiography for the prediction of postoperative myocardial recovery are comparable. However. the strongest pr edictor of overall improvement of post-operative left ventricular function is an increase of ejection fraction with a low-dose dobutamine infusion. (C ) 2000 The European Society of Cardiology.