Risk factors for mortality after coronary artery bypass grafting in patients with low left ventricular ejection fraction.

BACKGROUND

We managed to assess and confirm the risk factors for mortality after coronary artery bypass grafting (CABG) operations so as to map out the proper guidance of surgical strategy especially in patients with low left ventricular ejection fraction (LVEF) in domestic polyclinic like ours.

METHODS

Five hundred and forty-eight consecutive patients underwent CABG from December 1999 through August 2005 were analyzed retrospectively. Eighty-nine cases had an LVEF of 40% or less. All together twenty-two candidate factors were evaluated for their association with perioperative death using univariate and multivariate stepwise Logistic analysis.

RESULTS

When data from all the patients who had undergone CABG were taken into account, LVEF, left ventricular end diastolic diameter (LVEDD), mitral regurgitation, aneurysm of the heart wall, mitral repair/replacement, resection of aneurysm, concomitant aortic valve replacement, and perioperative intra-aortic balloon counter-pulsation (IABP), left ventricular assist device (LVAD) and cardiopulmonary bypass (CPB) all showed an association with perioperative death in univariate analysis, while an LVEF of > 40%, on the other hand, appeared to be a protective factor. In multivariate analysis, moderate to severe mitral regurgitation, aneurysm of the heart wall, repair of septal perforation and aortic regurgitation were proved to be risk factors. When the analysis was restricted to patients with an LVEF of 40% or less, such variables as age, LVEDD, mitral regurgitation, mitral repair/replacement, IABP, and CPB were qualified as risk factors in a univariate analysis. Age, moderate mitral regurgitation, aneurysm of the heart wall, CPB, left main coronary artery disease and female were associated with perioperative death in a multivariate logistic regression analysis.

CONCLUSIONS

Concerning the prognosis, patients who undergo CABG would have different risk factors when data from all the enrolled patients or data from patients with LVEF <or= 40% is compared. This is because low LVEF is itself an important risk factor. Regarding the low LVEF patients, the aggressive treatments including correction of mitral regurgitation and resection of aneurysm of the heart wall concomitant with CABG should be taken into account while planning the operative strategy to ensure the perioperative safety and prognosis.