Do the presence and amount of dysfunctional but viable myocardium affect the perioperative outcome of coronary artery bypass graft surgery?

Prediction of functional recovery after revascularization in patients with coronary artery disease and left ventricular dysfunction by gated FDG-PET

BACKGROUND

Traditionally, cardiac fluorodeoxyglucose (FDG) uptake is combined with regional perfusion for optimal evaluation of viability. Gated FDG-positron emission tomography (PET) may be an alternative technique for detection of viability because it permits combined assessment of glucose metabolism uptake and wall thickening (WT). In this study the value of FDG uptake and WT (analyzed from a stand-alone gated FDG-PET study) for the prediction of recovery of regional and global left ventricular (LV) function in patients with coronary artery disease undergoing revascularization is studied.

METHODS AND RESULTS

Thirty-eight patients with chronic coronary artery disease and LV dysfunction were included. Patients underwent gated FDG-PET to assess viability. Magnetic resonance imaging was performed before and 6 months after revascularization to assess regional and global LV function and LV volumes. Of the 213 revascularized dysfunctional segments, 133 (62%) exhibited functional recovery on follow-up magnetic resonance imaging. Receiver operating characteristic curve analysis indicated that a cutoff level for FDG uptake of 50% or greater yielded a sensitivity and specificity of 93% and 85%, respectively, on gated FDG-PET for prediction of improvement in regional function. Similarly, a cutoff level of 10% or greater for WT was optimal with a sensitivity and specificity of 89% and 78%, respectively. Improvement in LV ejection fraction was best predicted by the number of viable segments. Reverse LV remodeling could be predicted with a sensitivity and specificity of 89% and 65%, respectively, by use of FDG uptake of 50% or greater and 78% and 70%, respectively, by use of WT of 10% or greater.

CONCLUSION

Accurate prediction of outcome after revascularization (including improvement in regional and global LV function and reverse remodeling) is possible with gated FDG-PET by use of a threshold of 50% or greater for FDG uptake or a threshold of 10% or greater for WT.

Coronary artery bypass grafting in patients with poor left ventricular function

Coronary artery bypass grafting (CABG) in patients with poor left ventricular function remains a surgical challenge and is still controversial. The purposes of this study were to evaluate the effectiveness of CABG in such patients when performed without case selection on the basis of preoperative viability tests and to determine the predictors of postperative outcome. The preoperative, perioperative, and postoperative early and mid-term follow-up data of 273 patients with < or = 30% left ventricular ejection fraction (LVEF) who underwent isolated CABG between January 1995 and November 2000 were evaluated. Preoperative echocardiography and cardiac catheterization, and postoperative control echocardiography were performed in all patients. Follow-up was achieved via monthly periodical examinations in the first 6 months, and thereafter by either regular visits or phone contact. Preoperatively, 242 (88.65%) patients were in NYHA class III or IV, and the mean LVEF was 26.51 +/- 3.64%. The overall hospital mortality total was 14 (5.13%) patients. There were 44 (16.12%) late mortalities. Postoperative morbidities were observed in 74 (27.1%) patients. Two-hundred and two (93.95%) of the surviving 215 (78.75%) patients were in NYHA class I or II at 49.55 +/- 14.84 months of follow-up. Postoperative follow-up echocardiographic examinations revealed a mean LVEF of 39.66% +/- 5.43%. The improvements in functional capacity and LVEF were significant. Advanced age, diabetes, hypertension, cross-clamp time >60 min, bypass time>120 min, and severity of functional class (class III-IV of NYHA) were found to be the determinants of mortality. However, multivariate analyses revealed only older age and class III-IV of NYHA and CCS were predictors of mortality. The low mortality and morbidity rates as well as satisfactory postoperative improvements in functional capacity and LVEF measurements support the use of CABG without the need for any viability assessment in patients with left ventricular dysfunction.