Does the extended use of arterial grafts compromise the myocardial recovery after coronary artery bypass grafting in left ventricular dysfunction?

Objective: To assess the prognostic factors of myocardial recovery expected after coronary bypass surgery and the impact of surgical technique used, a prospective non-randomized study including a 1-year postoperative evaluation of left ventricular function was performed in patients with left ventricular dysfunction (left ventricular ejection fraction (LVEF) < 0.40).

Methods: From 1993 to 1996, 110 patients (mean age 61+/-11 years) were included in the study. The mean LVEF was 31+/-6%. All patients had preoperative radionuclide investigations based on the combination of stress/reinjection thallium single photon emission computed tomography (SPECT) and planar evaluation of LVEF; 88% of patients had reversible ischemic thallium defects. Two surgical technique were used: 53 patients received the left internal mammary artery with associated sequential vein graft, and 57 patients received only arterial grafts, internal mammary and gastroepiploic arteries. The mean number of distal anastomoses was 3.2+/-0.8 and 54% of patients had complete revascularization. At 1 year, all survivors had clinical evaluation and the same radionuclide investigations.

Results: The early mortality was 2.7%. At 1 year, 100 patients were surviving; on average, NYHA class decreased 1.9+/-0.8 to 1.4+/-0.6 (P < 0.01) and CCS class from 2.8+/-0.6 to 1+/-0.3 (P < 0.01). The mean LVEF increase from 31+/-9 to 34+/-10% (P < 0.01) and the mean LV end-diastolic volume decreased from 317+/-112 to 285+/-108 ml (n.s.). The postoperative improvement in LV function was higher in patients in NYHA class 3 or 4 before surgery (P < 0.05), when associated sequential vein graft had been used (P < 0.01), and in patients with low preoperative LVEF (P < 0.01). The postoperative LVEF improvement observed was significantly correlated with the improvement in left ventricular end-diastolic (LVED) volume and the improvement in redistribution/reinjection thallium uptake. Multivariate analysis showed that the surgical technique used and the preoperative LVEF were independent prognostic factors of the postoperative myocardial function recovery, with a significant positive impact of the vein use.

Conclusion: This study confirms the excellent clinical results of coronary artery bypass grafting (CABG) in patients with coronary artery disease and LV dysfunction; improvement in LV function can be documented objectively and is correlated with reperfusion of hibernating myocardium. However, the extended use of arterial grafts does not allow to achieve the significant myocardial recovery observed with the use of one internal mammary artery (IMA) and associated sequential vein graft; it seems to be related to the preoperative selection of patients, but a direct negative impact of arterial grafts was documented and leads to be cautious in patients with severe LV dysfunction.