A narrative review of redo coronary artery bypass grafting

Redo coronary artery bypass grafting (CABG) differs from primary CABG in several aspects and poses an array of technical challenges to the cardiac surgeon. The natural progress of the native coronary artery disease and graft atherosclerosis leads to occlusion or restenosis in those who have had CABG in the past, thus warranting a redo CABG. The patients undergoing redo CABG have a greater incidence of multiple co-morbidities compared to those undergoing primary CABG. Over the years the need for redo CABG has decreased in comparison to the volume of CABG surgeries. The database of the Society of Thoracic Surgeons Adult Cardiac Surgery has shown a drop in redo procedures from 6% in the year 2000 to 3.4% in 2009 and over the next decade down to 2% of the overall CABGs. Left main stem lesions, myocardial infarction and heart failure are encountered significantly more often in patients needing redo CABG. Patient scenarios more often necessitate an urgent or emergent redo surgery. There is a threefold mortality risk for redo CABG compared to primary CABG in the perioperative period. However, the risk for redo CABG per se is reduced from 6.0% to 4.6%, a relative risk reduction of 23.7%. A careful preoperative workup which includes high-resolution imaging, precise surgical techniques and good myocardial protection using cold blood cardioplegia are the cornerstones of successful redo CABG. The adoption of off-pump technique also contributes to good outcomes. Better outcomes for this high-risk population are apparent in surgical centers that have high volumes and greater experience in redo CABG. Patients with ischemia involving the left anterior descending artery territory with viable myocardium and intense symptoms despite requisite medical therapy, in whom percutaneous coronary intervention is technically not feasible, are candidates for redo surgery. Surgical revascularization is also preferable in patients having significantly diseased vein grafts and left ventricular dysfunction. This narrative review provides an insight into the incidence, patients risk profile, indications, preoperative evaluation and patient selection, challenges associated with redo CABG, strategies to improve surgical outcomes and prospects of redo CABG.